While I respect the decision to try and keep it stock I will tell you you this. I have tried just about every type of setup in the vewlix. While the stock jamma kit was nice for its time, the issue with it was the scaler. The scaler and stock monitor would work with certain systems/boards just fine and did its thing, but a lot of boards/systems wouldn't work properly, many because of sync issues/refresh rate. So you needed to add something like a DVDO VP50Pro to adjust the refresh rate and do some other adjustments. The newer taito monitors also had their issues with the scaler. But realistically the downfall is the stock monitor, fine to play modern HD games, not really great for older stuff with funky refresh rates.
I would honestly get a Jammafier, thats is basically my go to jamma kit for any modern cab. Couple that with your scaler of choice and a replacement freesync monitor and I think you can play just about any jamma game PCB out there without issues.
I am personally waiting to upgrade my monitors in my vewlixs to 4K oleds with gorilla glass and pair that with a retrotink 4k, invzim's jammafier will handle the jamma pcbs, I couple that with RGB's jamma extensions, by far the best I have ever used. So my Jamma chain in the cabs will be: Jamma PCB -> RGBs Reco board -> RGB's Jamma extension -> Invzims's Jammafier -> Retrotink 4K -> 4k Oled Monitor.
Goodluck with whatever you choose.