First of all, I love your product!
My order arrived today and the carbs are phenomenal. The engine is gorgeous. I posted a pic of my Trabant project as a reply to your meme on FB.
If I may suggest, offer a basic engine. Then have a “day 2” kit. Valve covers, intake, carb, aircleaner and headers. You do that with transmissions. It would be fun to order a custom engine by just ordering the partial block and hop up kits. You could mix things up with the parts without selling individual small parts. Moroso kit, M/T kit, etc.
At FM, I tried to develop variations up front. Tooling was a bit more expensive, but if a variant was required, it could be put into the market in a significantly shorter time. Also meant that all the engineering was done up front with no retro fitting later, at a much higher cost. At GMP, working with my counterpart at the factory, we came up with a matrix of 13 variations from a Mustang tool. Small block, big block, manual, auto, A/C, non A/C. 67/68, fastback, convertible, wheel choices. It was tedious at first, as this was the most aggressive matrix ever. However, once we nailed it….
Just a thought…