I saw a holley tbi unit for sale, it is the 510-502-6 model for the 5.7 engine. Will it fit a 305 5.0 engine????

It should AFAIK.

the TBI on 305 and 350 is interchangeable?

The TBI unit is the same on both the 305-cid and 350-cid. Both engines used the stock TBI model 220 when they came with TBI.

the unit itself is the same, but the ones put on 350's had larger injectors. if they were the same, they'd have the same part numbers.

Nice Pic!

thanks guys, i will get that TBI unit as soon as possible.