Not a A-body but a couple of questions about a 318.

Would a 9 1/4 rear out of a 89 Dodge go in my 84 fairly easily? Supposed to have a 3.55 suregrip in it. I have the 8 1/4 right now. 2.94 gears and no suregrip. Also on the Ld4B intake the gentleman said it has been gasket matched and the ports are bigger than 318 ports, said it came off a 340. Would this matter or make a difference going on my 318? Will post the rear end question later in that section to. Thanks everyone for all the advice!
might need a shorter drive shaft for the bigger rear end. I have mis-matched ports on my 318 right now, its a Weiand action plus. Works very well.