Ordered some Curil T2 following this recommendation and some from yesterday's forum:
https://vwparts.aircooled.net/Curil-T2-Engine-Sealant-Tube-p/curil-t2.htm
https://www.thesamba.com/vw/forum/archive/index.php/o-t--t-174439--.html

Amazon link:
Elring Curil T2 Liquid Gasket non-hardening, temperature-resistant sealing compound 60ml
https://a.co/d/2q2XDc1

There is a warning is in all the books to NOT use RTV to seal aircooled VW case halves EVER, at least according to the instructions on the bottle. Typically, when applied in an amount big enough to make a "bead", what squeezes out of the gap *inside* the case comes off and gets in the bearings, oil pump, and lots of other places like this:
https://youtu.be/cySXe8a62a0?t=710

The engine in the link below shows the other reasons why - it dries HARD (whilst the case wants to shift a miniscule bit during every heat cycle) and does not typically CRUSH thin enough for the case to retain the main bearings:
https://www.thesamba.com/vw/forum/viewtopic.php?p=5055180#5055180

One user reports an "expert" method to make RTV work, if you so choose:
https://www.thesamba.com/vw/forum/viewtopic.php?t=691163