The 73100 springs are what is installed at the moment. I also talked to Butler now and they say the 73100 will technically work, but he cannot say if there may be a problem with valve float. They recommend the Edelbrock 5845 and I guess I will buy these springs with a spring compressor tool (from Proform). Don't want to risk more than necessary.
I hope the tool works well with the heads on.... good news is we already have a 14mm plug for compressed air
I wish I had the options and opportunities you have (and the prices). But in the end we will achieve our goals. Glad you help me out and share your experience with me. Maybe one day I'll get everything sold and move to the US... gets more and more complicated and expensive over here...