Tim here's some info for you to check on your 307...1) like Billy said you want to claim either 71 or 72 as their rated @ 175 hp not 195 like 70...with the same spec. now then go look @ your engine & see what you have...70 307 has a 183 # intake & 185 heads. the 71 & 72 use 991 or 339 heads the 71 has a 465 intake & the 72 has a 936. If you do in fact have a 70 engine their's 2 things you can do 1 is look for the right heads & intake or 2 write NHRA & ask them to reduce Hp on all the 307 68-70 as they have the same spec as the 71-72. Good luck & listen to Billy he knows his shxx!