47-55.1 Opinion - swap the S10 rear end now or later?

[hobo]

Okay, my '53 truck is a Frankenbeast anyway on the S10 frame, dropped spindles, chopped top, and shortened bed. It will only be a cruiser but I AM building a nice sbc 350/383 for her, which could likely kill the 7.5 open rear end if my foot gets heavy. And, as a car guy I WOULD like to have a posi in her. I'm debating whether to build her with the current 7.5 rear end and address it later or, since I'll have the bed off anyway, swap the rear end with either an 8.5 posi out of an S10 Blazer or narrow an 8.8 out of an Explorer (since one side is 3" longer than the other).

Thoughts or words of wisdom? I'm leaning towards doing it now vs. later.

Thanks all!