not to sound like an S-talker but let me get it straight.

you're taking the 305 out, refreshing it with the new parts you're buying etc.
then you're putting the 305 back in
then you're going to get a 350
swap the new parts from the 305 to the 350
then swap the 350 in.. ?

if that's the case, why don't you just save your money up now for the 350 and swap that it.. just seems like it would cut out a lot of uneeded wasted time.

either way the car should be fun with a 350