I run the McLeod street twin clutch. It's great for racing and street driving, BUT it does not like being in traffic! I won't recommend it for anyone that uses their car in heavy stop and go traffic. I did a local parade and from having to continuously slip it in the bumper to bumper traffic it got so hot it basically welded itself into a solid mass! But knowing that, I'd still buy it again! (I think they run around $1,400 now?)
You basically have a few options for the Oil pump. You can go with a new stock pump and swap out to a white spring ( the spring controls the oil pressure, White is the higher pressure ), or go aftermarket, the Melling pumps are good units IF you get the HD units, the stock replacement pumps have had issues with breaking.
For the pan Canton is a good unit, it's been around for a while but is not cheap, but now Moroso is making a pan and it cost less. This is the pan we have on order for a car so I should be able to report back in a few weeks how it compares to Canton's.
I run the melling HV pump and the Canton Race pan and I have 65 PSI and idle and 80 in the upper RPMS.
I'd suggest when you go parts shopping for your bottom end to look at quality ( yes more $$$) cranks. I have seen in person two of eagle's economical forged cranks snap! These were the cranks rated to 500HP and were in N/A LT1 383s that were right near, or just over the 500RWHP. Knowing that, spend a few extra dollars and go with something designed to handle a bit more.
Stock ported heads that are fully ported, larger valves ect. will support 500HP, You want to have your cam match the flow rates so that you keep the velocity up. That said, if you think down the road you might want more power then you should think about aftermarket heads now. Even LT4 heads and intake will give you good potential to grow. There is a local guy with LT4s making 500+ N/A and in the 800HP range with Nitris.
But aftermarket heads will certainly outflow anything you can do with stockers. If you need that kind of flow?
One other point on using stock heads vs. aftermarket. Because of the small chambers and how far the piston sit in the holes on a stock block, when you get your block machined I suggest not getting it zero decked. You can run into piston-to-valve clearance issues with stock headsthat you wouldn't with larger chamber aftermarket heads. So keeping the pistons down in the hole is a good thing.
When I assembled my engine ( was zero decked and I didn't know that was bring done, so i learned the hard way!) and I had custom pistons made - stage III stock heads, I didn’t have the clearance I wanted and it wasn't an option to cut the pistons. So I had to switch to a slightly thicker head gasket and also dropped the lift on the cam a little to get the clearance I wanted. Now I went a bit big on the clearance, but being the engine was going to see high RPMs and is a manual I wanted some extra clearance so if I missed a shift and over rev'd I was less likely to smack a valve.
And not to be a jerk, but make sure you price everything out before you dive into the build, to do it right you don't want to be cutting allot of corners, and after you build the short block or long block you still need all the supporting stuff as well.
I started my build with a $5,000 budget ( already had heads and blower ) and went thru it all before the engine was even finished being put together! Things come up and plans can change. I'm 100% not trying to tell you not to do this, just plan things out. Nothing sucks more then running out of funding 1/2 way through a project!