If its just a flat pce of metal....then I mis-understood.Was thinking a cap like a Marlin lever.Where its a 3 dimensional affair.
If you hate wood....and I understand....start focusing your attention on the transition from wood to metal.Uhhh,it happens alot on guns,haha.Try some experiments with Heli-coils(threaded inserts).Most woods will "tap"....theres some difference in real soft woods,but that isn't a problem with quality gunstocks.
You'll have to play with the clearance holes for tapping.And you won't use lubricant...use air,keep a steady(bout 40 lbs)blast directed at hole during tapping.....otherwise its the same as metal.backing tap out to clear chips and such.
The problem with old gunstocks is more often than not,they're "oil rotten".You'll either have to go "deep"....or go,big(helicoil).The use of chemicals for cleaning wood is sort of subjective?But the major failing is very similar to auto body prep work.You use W/G(wax and grease)remover....BUT!!!!...if you don't wipe it off(with clean rag)whilst wet,you're just spinnin your wheels.Its the same with gunstocks.......you put the chemical on(acetone,W/G remover,ect.ect.)but then it just sits there.All you're doing is "moving the muck around".It never really gets removed.
Going deep with fastener is fine as long as its getting away from the problem.Riflestocks are relatively long and narrow.......so thats where "big" comes in.You're trying to get as much surface bite as possible.Its also easier to get the stock "clean-ish",closest to the surface.
Good luck,sounds like you're studyin the problem and will come up with a VG fix.