G'day Justin,
My engine mounts for the RB30 motor came from Castlemaine Rod Shop - bolted straight up and came certified for engineering. I was already running a red motor, so the mounts on the front end had been moved back.
I used the RB30 gearbox mount and had a mate weld up some additional bits - was fairly simple but very solid and works well.
You could probably get all you need - engine mounts, gearbox cross member, etc from CRS or similar places. The most important thing before you buy anything is have a well documented and thought out plan and stick to it. Some of this stuff can be very costly and once you start cutting things up, there is no turning back........
But it is all good fun and very rewarding when finished
Good luck with your build,
Cheers, Graeme (JOX515)