To follow up on this, I fitted the MOMO Start seat into the car and crawled in to test sit the seat. Danged if I'm not higher than I was before. The MOMO has thicker fiberglass at the bottom and thinner padding on the seating surface that actually has me 1" or so higher. My goal was to get clear of the bars over my head, the MOMO puts me up in the "rafters".

$#@*!

The next plan is to reuse the seat I already had in the car but to remove the padding and try to sink in a bit.

Thanks for the info.