OK. Foundry reckon it's no problem to copy accurately with no alterations neccessary; originals were probably cast in LM4 (high magnesium) favoured by OEM's because it doesn't require heat treatment after casting. Cheapo. Downside is that the Mg oxidizes really quickly = spongy and porous before you know it!
Mine will be from LM25, heat-treated and will last! I'll try to get the core master made this week and down to the foundry on Friday; will have a first-off for approval before we get too far in.
I think that the price point of £90 is achieveable, but for a first run of 10-off or 20-off I need an indicator of demand...List below if you're interested.
1. Me!