Mine's a v6 but it is the same principle. At first the only reason I went v6 was to keep my a/c but now I'm not keeping it so I coulda went v8.

v8's are 4" longer than the 4.3 so your fan will likely have to be a pusher rather than a puller.

Motor mount plaement will be the same. I used motor mounts from a BBC truck. But they are a direct bolt in since all 90* GM engines use the same mounting bosses for the blocks.

-Chad