Assuming using a stock block?
Keeping the block & bits itself intact is the easy part: spend money.
The rest is partially money: 7mm valves, biggest double-tapered pushrods that will fit, titanium? collars, beryllium? springs, Spintron test everything.
Offset secondary rockers as jackshafts to correct pushrod angularity have been used successfully (but not in race cars, or recently).

The interesting part, to me, is to force someone to run an FEA program on the Barton rockers to isolate where mass can be safely removed without structural compromise, which may take many passes to get the lever ends slimmed down (as we say "make it all the same blue color"). Once this is done, no brain surgeons are needed, a small boy with a Dremel can duplicate the work. Wouldn't it be nice if Barton donated a (slightly used) set, in exchange for valuable data he may not have?