Re: Where did you buy your reman engine from?
Whoever you decide on, make sure they specify what parts they used throughout. You should know what are the maximum overbore and other specs. It is key to know pistons, heads and cam, to make sure it is equivelent to yours. Also, check what you can (casting/part numbers) after receiving it. I have seen posts of 305 heads coming on 350s, and other "odd" configurations. Also, different from stock merc or volvo cams seem to be common.
While I have a working knowledge of sbc changes through the years, not the 4.3L. Somewhere in old threads was a link to 4.3L vintage info. From my understanding, there ary many more slight changes through the years, that you should have some idea how that may effect you, or identify before installing.