If you have 250hp and I gather it's positive displacement boost, you'd do well to go down in gear ratio, the 3.55:1 wouldn't be too much. As power goes up, the gearing need is less, the fastest cars have less gear.
When I do a 306 build for my 99 work truck, it's already a 4.10:1 4WD truck now. I'll build the 4R70W with close ratios(the AODE planetary set of parts). That moves 1st/2nd both closer to 3rd/4th, which don't change. The difference is similar to two gear steps, say a 3.27 versus 3.73, so with 4.10's the truck will be the same as a 3.55 truck in 1st and 2nd, and 4.10 in 3rd and 4th. That would be poor for a stock 302, but mine will probably hit 250-275hp, which should be fine.