I can give it attempt for you, being within europe might help. I also have a dutch friends who live in Sweden which I could try for you
I forgot to come back here and check this thread, I'll send you a PM later. Boots on the ground in Sweden might be part of my answer.
If you need larger buckets for the head. Have you asked enem? I know they sold 37mm ones. Not sure about 38mm buckets for sale there.
I did reach out to Enem and they have a supplier for more expensive 38's but there was no stock. They offered 37.1's which might just do it but there was also no stock there. I will say Enem is super responsive and great to work with.
I ordered 38's from KL Racing... not sure why I bothered they are way to thick at like 6mm and don't have enough post protrusion to just mill the post down.
I also asked Supertech about custom buckets. Good news! They can produce custom buckets to exactly the spec I need! Bad news... minimum purchase quantity is 160pcs. So I just need like 18 of you to put together oddball 8 valve heads and group buy some buckets with me!
I've found all sorts of COTS buckets that hit every dimension except length... it's that ~35mm length that kills me.
Anyways, so the RSI head is bagged and tagged sitting in the morgue here. Will waste more money on it someday. Somewhere in Sweden my next head is taking shape with Erland, he's just waiting on a cam and shaping combustion chambers. Lots of back and forth there on compression ratios, chamber shape, squish etc. Erland really wants me to run flat top pistons, I really don't want to rebuild my bottom end around a different set of pistons. So we're trying to find the right compromise to run the old Wiseco Wave Guides and potentially support flat tops if I do another bottom end.
I do toy with the idea of concurrently building a 2.5l block with the crank in the shed, put pistons in it Erland wants etc... then I also start looking at b/s58 pullouts and total loss cars and thinking gee wouldn't 800hp be fun?