Newbie dropping 350/auto into my '59 chev

[Tom'48]

I am new to this forum but have been reading some of the posts and replies and am very impressed with the knowledge and helpful people here.
My project truck is a 1959 Chevrolet 3100 short box fleetside,with large rear window. The truck is almost all original,little rust,and very straight. Although the truck engine runs great,(tranny and drive train is ok), I want to remove it (been told I'm crazy) and put in a 350 with a 7004R tranny. I will get a 10 bolt gm rear end with a gear ratio of 3.10-3.73 range to go with it,have 3 choices,to pick from,(76 monte carlo,76 olds omega,78 camaro). I want to add power steering & power disc brakes to improve handling & safety. I can't bring myself to cut the front frame and add a clip as I want to keep the truck somewhat original. Will I have any problems dropping this engine/trans in? Should I order the (kit)crossmembers available to mount the e/t's? How 'bout the power steering and brakes. I have a saginaw gear from a 2wd suburban,however I wonder if I could use a rack&pinion from a late model GM or other? How 'bout the power brakes, any suggestions here. Sorry for the length of this,but I have so many questions? Thanks in advance Tom