Just a suggestion....

Before you do anything to the engine, might want to determine what condition it's in...How many miles on it? Does it use any oil? Any leaks? Then it would be a good idea to do either a compression check or (better yet) a leak down check...

The key words to me are "recently purchased".... Do you know the history of the truck? Is it the original engine or did somebody drop in a 305 when the original died...Seen any number of 305's passed off as 350's to an unsuspecting buyer! Might want to get the casting numbers off the block and heads and make sure of what you have, first...