Yes...they are the same bolt pattern.
yes
Absolutely! It bolts to a 305 exactly the same way it bolts to a 350... It's completely interchangeable.
Yes you sure can. There the same.
The headers for a 350 and 305 are the same.
yes
no
Probably not. It will likely be too short.
yes, the 700R4 transmission is the standard trans for the K1500 with a 5.7 350 engine. 305 is also with the 700R4 transmision.
yes its the same but i wouldn't recomend using the stock trans unless rebuilt
yes a350 trans and 400 use the same bellhousing
You will need to have the heads for the 305 bored out to the same size as the 350. I disagree: you can use the 305 heads on the 350 block but you will increase compression as the 305 heads have a smaller combustion chamber. The critical dimension is valve clearance. If compression ratio is a critical consideration, different pistons may be available which will bring the combustion chamber back to size. the 305 is from the 3.671 inch bore family. The 350 is from the 4.00 inch bore family. All small block heads have the same bolt pattern.
You can not change A 305 to A 350, If you want A 350 you should buy one, You can use the heads on the 350, They are very likely GOOD castings, they will increase compression, This will improve the power of the motor, but it will be limitted because the 305 heads will not flow the volume of 350 heads, this means your Max RPM. will be lower than with 350 heads, its A give and take, If you get A 350 it will be A dirrect exchange with no mods. if you use the orriginal heads, and may be even if your 350 has good heads and they are drilled the same,The bolt pattern will be the same, no need to measure, just make sure ALL the holes are present, The harmonic ballancer is thinner on the 350 than on the 305, but the offset is the same to the front, so do not worry about the distance from block to front of ballancer, USE ALL THE BOLT ON PARTS FROM YOUR CAR, they will ALL fit the new motor,,,,,flywheel,starter,exhaust,tranny,pullies,brackets,fan,intake,carb,distributor,valve covers,,,,,, if you replace any of this, it may be hard to hook up everything. , Jamison.