Towing with short bed?

[Hobbs81]

I am restoring my 68 c-20 to be my tow vehicle, shop truck. I'm retaining the stock running gear (disk conversion with hydroboost). I'm kicking around either a BBC or LS (leaning BB- just cooler). I intended to leave it long bed because it should tow better. But I also want to do a few car shows / cruises so would prefer to shorten it. How do the short beds seem to tow a car carrier with probably another C-20 on it? 😊 Opinions on the engine? I'm thinking TH 400 trans with the gear vendors overdrive.