See if you can’t get in touch with the last owner of the car for the cam specs. This would be the #1 important item to know. Valve size is not a big deal deal. The 904 is better because it is lighter in overall weight and requires less power to make it work. The difference is a tenth or better in a race car. Swapping the 904 to the 727 will require your driveshaft to be shortened & use a different yoke.
Try and get a hold of him again. Be a pest!
Until he says Uncle.
Or swap in your own cam ;)
