I run a 7qt Moroso baffled oil pan. Their standard deep pan would not fit into my bilge so I use their wide flared pan that's not as deep. Close to 7.5 qts oil capacity with the filter and cooler and lines. I also have a windage tray.
Using a left handed dipstick with my block.
I would not worry much about the #5 category. The only thing I do is add two large magnets to the bottom of my oil pan along with smaller ones near the oil drain holes in the heads. Just make sure everything has proper clearance.
I'm in the same boat as you. Building a mean 355. I'm retrofitting to a hyd roller either the Lunati Voodoo 219/227 .515/.530 112/106 or the Comp Xtreme Marine 218/224 112/110. I'm going to run a 22P Clever and spin over 6,000 rpms though. AFR 195s, Performer RPM, Forged I beams, 4340 ESP crank, Forged TRW's 10.5-1 SCR.
Sounds like you should have a nice setup coming along! Just remember the Alpha is your weaklink. No WOT holeshots, if the drive comes out of the water don't come back in under power, after WOT runs slow down gradually. I've made my Alpha live since 1992 using the above guidelines.