first,just buy 302 pistons,use 283 rods and a small journal 327 block.
Problems: 283 uses a small pressed on ,one piece balancer,many prefer to use the bigger 2 piece balancer. If you have a 350 block,then buy a large journal 302 crank. then its worth upgrading the rods.large journal rods are more common so price is fair.
If you have a 283 block then consider building a 292 (060 over 283) you only lose 13 inches.
Depending on how much horse power you want? its easy to get too much cylinder head on that little engine. A small runner 2.02 head will make lots of power. I wouldnt build much more than 425 horse power for a normally aspirated 5 liter