84 blazer engine swap

i need to know if you can put a 4.3L or any thing bigger in a blazer with a 2.8L with out doin much or any mods.

i need to know if you can put a 4.3L or any thing bigger in a blazer with a 2.8L with out doin much or any mods.
I know you would have to change the computer if you go to anything bigger than a 3.2. Thats what I have been told. I have an 85 with a 2.8 and have asked the same question at the dealers. By the way does your 2.8 have a knock in it. That's the problem I am having with my 85--2.8.
I was told that all of the 2.8's had that problem. Heard anything? I have heard there many Blazer owners with the 2.8 that have the same problem.
Gary