What motor to go with?

I believe the 904 'most yrs' shared the same 1st gear ratio as the 727, others were even lower.

the 998 & 999 [904 family] have the lower 1st & 2nd gears...that swap into the 904 with ease.

They are raced all the time.
I know lots of guys racing 904s but they are puting tons of money in them to make them hold up. Why bother wasting money to tuffen up a 904 if he is going to already have a 727. Spend the money on your motor. I can smoke a stock 904 in my Duster in about 20 min. Got sick of laying under the car. If 904s are so nice how come they never put them behind a big block? Was wrong on the lower 1st gear. 727s have a 2.45 1st and 904s have a 2.70 1st witch they needed because most 904 cars were extremly high geared 2.94-2.76s