I thought about using a girdle simply as a spacer
to increase oil pan capacity, I might even cut away
the main cap tie-ins,
Anybody make a 1-in thick aluminum girdle ?

Just have some kickouts welded in the pan but you could have some bar stock welded to make a spacer.My dragster styl girdle is only 3/8"

our stock bcr girdle is 1/2" thick and I've made an aluminum version before. 1" thick aluminum would be no problem.

Anybody make a 1-in thick aluminum girdle ?

On my pull tractor I made a 1 inch thick one and its kept the crank and block together ever since.

But for your purpose id think there would be a easier/cheaper way to increase oil capacity.

You could run an ext filter setup and use a industrial type size filter or?

https://www.onlinemetals.com/merchant.cf...&top_cat=60 The cheapest would be this and have it weldid I think.Only 35$ and then welding cost maybe 60$ and you drill it.
ps: other than the pan welding deal.

Make sure you can get the right stud length before adding an inch to the main stud length.

OK thanks gents, I need to mock up the block in the frame anyway
to see what I can get away with spacewise.

Increasing pan capacity to achieve what?
It might keep the pickup covered a bit more (especially with no baffles), if the pickup is lowered by the same amount.
The oil temperature won't change much.
Getting the oil away from the crank might be better than adding oil.
What other oil control do you have in the pan now?

Polyspheric, More pan capacity but perhaps not more oil (but maybe).

I think it would make oil control easier by way of keeping the oil
level farther from the crank. It would also, hopefully, help to keep
oil supply near the pickup more consistent, but this would have to go
hand in hand with good baffling.

Yes, I would absolutely lower the pickup as well.

I'm not concerned with oil temp problems at this point.