Your lens choice is very specific

a 90mm Tilt-shift lens

yet your camera and lighting gear choices are much broader:

my DSLR body

Transportable studio flash gear

Did you pick the lens because you recently used it, liked it a lot and now subconsciously want to use it for that task? Is the other equipment just a necessity to use that nice lens and thus doesn't need further specification? Whether that's true or not for you personally doesn't really matter. The point is that you should always pick the tools according to the job, not the other way round. Let's take a look at the job again:

Which equipment would be required?

Is tilt-shift really required for this assignment? Really? I don't think so. What properties of a lens are important for product photography?

• It is capable of displaying the entire product and maybe various details of it. Having different focal lengths at your disposal is always an advantage. You have to carry a lot of gear anyway, bringing two or three lenses, maybe even a zoom seems to make more sense than a single prime lens.
• It represents the product as it is. This means a lens that does not introduce color shifts, distortion, etc. That hints at using prime lenses as they usually have good optical quality.
• It allows close focus. If you cannot get closer because of the focus, that's a huge restriction when working with products. Dedicated macro lenses have an advantage here.

I'd pack 2 to 3 prime lenses of different focal lengths from slight wide angle to slight tele. At least one of them would be a macro lens. Adding the 90mm tilt-shift for creative possibilities cannot hurt, but it would not be my first choice, because it is not required. Same is true for autofocus, btw.

There are other properties that can be deduced from the description:

a large range of dry goods products

This is not a single image. There might be 100 products or more. How many images can be taken with a charged battery of the camera?

Bringing a second battery and a charger or better an adapter to power the camera via cable directly from the outlet in addition to the battery in the camera should be considered a requirement.

all images to represent the products accurately

You cannot rely on the lcd display of the camera to check the images. Shoot tethered. This means to bring a laptop or computer with good calibrated monitor and the necessary cables. You don't want to come home with a raw file and be like "yeah, errrr the red of the tomatoes looked errrr exactly like that". This also means to bring some color target for color accuracy.

Mount the camera onto a tripod or comparable equipment. The goal is to have a consistent look for the products. Keeping the camera mostly in one spot helps with that.

How about the lighting gear?

The subject is stationary. You can compensate lack of flash power with shutter speed (if you use a tripod). Recycle times are not the biggest issue either. What's more important is that you have enough mounting equipment to get the lights into the positions you want them to be. This makes strobes with separate power packs more suited for the job, because the heads are lighter. You have less stuff getting in your way.

The lighting should be even. A light modifier that creates soft light over a large surface would be ideal.

from soup tins to boxes of breakfast cereals

The products are packaged differently. The surfaces of the packages reflect light differently. You should bring reflectors and flags of different colors and sizes to locally block or enhance reflections.

Last but not least, there's one more piece of equipment required: you. Be prepared. This is boxes of breakfast cereals which you can try to photograph beforehand. Train yourself with the equipment. Come up with strategies for lighting. Possibly an order of products to shot. Have a schedule for the assignment. Arrange intermediate talks with the client to get feedback and be prepared to adjust to whatever they want. You are not paid to figure out how to do it. You are paid to do it.

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There is opinion in this answer. Not every item I mentioned is necessarily required to get the job done. The point is to have a thought process that involves the entire workflow and process of the shooting. Listing what's required means knowing why it is required.