My "new" 1968 GMC C30

[My Alter Ego]

Been around the forum since 2009 and have enjoyed and appreciated all the information that's available. Oddly, I don't think I've ever posted any pics. At any rate, I just purchased this 1968 GMC C30, 327, 4spd, PS, PB, PTO, #'s matching latbed dump with 83K original miles. My immediate plans are to swap out the front and rear suspension in favor of those from a 73-87 dually donor. Since it's a #'s matching truck, I'm torn as to whether or not I want to replace the engine with a big block. I'd sure appreciate any/all suggestions, advice and/or knowledge relative to these plans. Thanks in advance.