Best year(s) 904 for a street/strip car?

Vin# pad will also tell year.
I run a 84 lockup 5 clutch low gear set from a Diplomat. TF2 shift kit, lockup circuit plugged, Turbo Action 10" S800 26 spline 3200 tight converter, 3.91 gear. 340 375-400 real world hp, Launch car at 2k 1.65 60', 11.77 best so far in ok air. I pulled the tranny after 400 passes and it looked good so it when back in with new seals only. Lockup input shaft is plenty strong for what I'm doing street/strip drive 100 miles round trip to the track.