1992 full size blazer questions

[Tseats]

Hi everyone I hope someone from this site will be more helpful than the last site I tried using. Ok here is what I got 1992 k1500 blazer with tbi 350. My question is if this motor can be changed from flat tappet to roller or am I better off to buy a new crate long block L31 vortec 350? (if I can use roller cam I'll put new 906 vortec heads on it) I'd like to run a lt4 cam or something of that range.is like to build it up and get 300rwhp. It has true duals already. I've been thinking of changing the 2 barrel tbi over to the 4 barrel efi unit with self tuning if need be. And I will not do an ls swap I owned two before and don't like them at all that's why I got rid of them for a 350 again and they drank more gas than my blazer does 10mpg and 13mpg is what I got on the ls trucks my blazer get 19mpg any help from you guy would be great And no emissions where I live