It all depends on the block. There were certain 283s that could go an 1/8.........but NOT many that would last. I do think I have one that is an original ChevyII block , with the screw on oil filter. Those were supposed to work? Easier way was use a small journal 327 block with a 283 crank.
If you are doing a lot of "hidden" work, what difference does it make if you don't have original heads.......nobody is gonna see the numbers with the valve covers on???
If you pull the drive shaft and start the engine and put it in drive, you run the risk of pumping all your ATF out on your floor, through the tail shaft housing.
I drain the master cylinder before I do a brake job with a turkey baster or a Mighty Vac, clean it out as best as possible and refill with fresh brake fluid. I NEVER push the fluid back into the master. I always open the bleeder and push the fluid into a bottle. Close the bleeders, then push the...
Before I replaced anything, I would drain and flush the brake fluid. If it's black and looks oily, it may be. If it is , you run the risk of ruining all of your new parts. AND I would replace everything in the hydraulic end of your brake system.