250 integrated head to a 305

[fred_e81]

First square so bare with me,

I have a 79 stepper with a 250 integrated head 3 on the tree converted to floor shifter by PO. I am having issues with it idling and stalling out when I put a load on it. I know these heads are garbage but, I have an opportunity to buy a 305 complete with accessories for $400 obo (engine is still in the vehicle to test out). My question is will the 305 mat to the 3 speed tranny that I have on it now? What exactly will be needed to perform the swap? Money is kind of an issue so getting a different tranny is out of the question for now. I bought the truck in October and I just want to enjoy it for now. Any help is greatly appreciated, thanks!