There is an in-date Recaro Profi XL for sale on RL. I have that seat in my Boxster, floor mounted, I am 6'2", 34" inseam, 36" waist, and the seat is awesome for "bigger" folks.
If you are slender then possibly the regular Profi might be good for you, that is what I have on my passenger side. For me it is like a child seat... I can jam myself in but it is not comfortable.
If I were to build a racecar I think I would look seriously at the Bimarco Grip seat, it is an FIA Halo seat.
BIMARCO - sport seats and racing shells manufacturer - FIA homologation
They used to sell on ebay but I think they are selling direct now, the US rep is Michal Chodan
bimarcousa@gmail.com
I think one or two folks on here may have this seat and I think some racers on RL do as well. half price or less of some of the other seats.
Are you in NC (RDU?) Check with the Carolinas Region PCA as they have an active HPDE program and you could probably go to one of their events and sit in a lot of seats to try them.
Steve
[Edit - looks like they are back on ebay but with slightly higher prices..
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p4340.m570.l1313.TR0.TRC0.H0.Xbimarco.TRS0&_nkw=bimarco&_sacat=0 If you buy 2 seats I think they can ship them in the same box for only 1 shipping charge.]