904 or A518 help

Lee, pay off (In fuel savings/money in pocket) for this work will be a long time coming. But then again, we old car owners care little about this. If it an issue, then a cheaper way is re-gear, cam and tune it to work with a broom stick cam and 2.76 gears. Or less gear.

The bennifit of the extra get up and go with the lower first gear ratio is nice, but slight.
If you allready have the tranny, your ahead of the game. The rear mount from the trans to the car body is the only fabbing/thinking you'll have to do. Then, of course, shorten the driveshaft.

The O.D. ratio is .69. Multiply this by the rear gear ratio for the new final drive ratio and figure it out from there.

4.56 X .69 = 3.1464
4.30 X .69 = 2.967
4.10 X .69 = 2.829
3.91 X .60 = 2.6979
3.73 X .69 = 2.5737
3.55 X .69 = 2.4495