If I am not mistaken, the A/C.net cranks are custom done by DPR, same as Jake's cranks. DPR's welded cranks are by far the best; aircraft guys in the know use welded cranks all day, with no issues. Save the money between a welded and billet crank and spend it cryo'ing your engine or even to spend on ceramic lifters and ARP Hardware, or heaven forbids, Nickies :-). For the type 4, a cheap alternative to forged pistons are KBs. On the type 1, i've match honed cima/mahle 94a/b s to Nickies.
Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance