To stroke or not to stroke?

[Kawtriplefreak]

My last motorcycle ride was at Deals Gap on May 11th. Spousal health issues and other problems have limited my shop time to nearly non-existent.
I did manage to get the gas tank drained and removed from one of my two currently blown up RZs while warming up my  tractor last weekend. I have decided the white RZ will be the 1st to be rebuilt as it appears to be the most damaged of the two. It is seized and will not turn over.
Long story short I have been doing some research and have decided one or both bikes (depending on the extent of internal carnage) will be getting a 4MM stroker crank for 385 CCS of displacement with 115MM rods. This will require Wiseco 795 pistons or equivalent and either a head modification or an aftermarket head like Wicked makes to account for the 2MM of piston hanging out of the top of the bore after the crank install. I am hoping none of the cylinders are damaged as they have all been ported and I would rather have the YVPS System intact.
Failing that I may do a 392 or 421 with aftermarket cylinders which will be quite a bit more expensive as it  requires either cutting up my FPPs and or Spec2 chambers for the different spigot or going whole  hog with a set of custom pipes made  for the conversion like Wicked or Mutts Nuts in the UK.
I don't want to go beyond 4MM increase in stroke as it requires trenching the cases and from what I have read a marked decrease in engine life. If anybody has some experience with this please enlighten me.

[m in sc]

you'll need new pipes to make it work right.

[rodneya]

A 421 will need specific pipes and bigger carbs to get full performance, but I think the power it makes is well worth the $ to build. Shearer also makes pipes for a 421 RZ.
A 385 will still work with stock carbs and the pipes you have, but you may need to run a spacer under the barrels or adjust porting heights to work with the 4mm crank. If you are going to get a head from Wicked you could ask him what would work best for a 385 with the porting you have.

[Kawtriplefreak]

Thanks!I am in the research phase and I appreciate the knowledge. I am leaning towards having a Yamaha head machined and set up for o-rings after reading some bad things about the custom heads with removable domes cracking. I haven't called Wicked but I did send an email requesting info.
The white RZ has a stage 1 port job from Spec2 and head work from Spec2 as well.
The Gray Ghost has unknown porting.

[Jung]

You need to adjust the ports for the extra stroke. RZs already have pretty racey port timing as stock, so I guess it would just involve lowering the floor of the exhaust and transfers. Doing that would still give something like 192/122 on a 4mm. If the exh port has been raised in the past, you're going to end up with a LOT of exhaust timing, which might not be ideal.

[Kawtriplefreak]

I understand. Thank you.