@Larrs888 This may be too late, but i got a PAL NES Frontloader, AV Famicom and RGB N64 from oldskoolconsoles pre-modded. The modwork is clean and well done, can't fault anything. His prices are very reasonable too. The consoles were in decent condition and well packaged so i think sending yours in would be fine.
However, the only problem i found is the way they were hooked up to the multi outs. Both AV FC and N64 had composite cut (as must be done for these mods) and then had TTL Csync wired to them. Which means anyone using a standard sync-on-composite scart cable, or hell even a composite RCA cable would be sending TTL Csync to their tv. I was worried about this till i found out the supposed "TTL" Csync of the NES and N64 RGB boards actually only give about 0.7Vp-p over 75ohms (which is within 75ohm spec), as apposed to something like 2.5Vp-p which could cause damage. Also while the N64 had TTL wired to the composite pin, CS75 was wired to pin 3, which means someone using an NTSC SNES CSYNC Cable would be dropping 75ohm level csync over a 470ohm resistor.
After querying all this with him, and suggesting he just try and match the NTSC SNES in terms of sync output options, he got back to me thanking me fir my help and saying he'd take it on board, very nice guy. Even helped me more recently identify why my PAL frontloader had weird interference all over the screen (turned out to be a power issue, damn crappy NES regulator.) Would reccomend getting a 9v 2a psu if anyone encounters any issues, before ripping apart their NES RGB board on a wild goose chase.
Anyway where was i? Yes very good modder, just maybe tell him how you want it hooked up. Hope this is helpfull, it's my first post here, (hello everyone) made an account just cause i can finally answer something
I've attached some photos of his modwork.
https://i.imgur.com/y4Hp0dx.jpg
https://i.imgur.com/Rt0F1ig.jpg
https://i.imgur.com/yFcgG3x.jpg
https://i.imgur.com/Y3ydqk1.jpg