Check with
Raby's Aircooled Technology about one of his MassIVe Type 4s; he's on this side of the U.S.
170HP is very do-able (he gets 150 dyno-proven HP out of his 2270 T-IV's), but "... 50-70 shot for the track (?)" is just asking for torched hardware; I've seen great drivers in lower HP cars drive circles around high HP posers.
Just build/buy it right the first time, and leave the NOS for the ricers.