The gas tank does not vent to the filler neck. You get a CEL when the filler neck leaks, not when it's sealed.
The tank vents to the vapor recovery system; ie the charcoal canister under the hood. This should work fine with your EFI without any changes. All you need to do is delete the carburetor bowl vent to the canister.
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination ATs, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
ECO Green: '15 FCA Jeep Cherokee KL Trailhawk