Yeah you can bypass the gauge . Me personally , I like keeping an eye on what's going on under the hood . In my opinion , the factory gauge is the weakest point in the charging system . But "if" everything is working properly then there shouldn't be an issue . I would say about one out of ten have gone up in smoke . Normally because of over charging , bad wiring , or just plane old . If you don't want to take the chance of going thru the charging system wiring an hooking up a factory gauge again , then you could always wire up an aftermarket one just to keep an eye on things . You should be getting between 13 and 14 1/2 volts at the back of your alternator with the engine running . The 12 and 13 volts your getting now could be because the alternator isn't putting out enough or your battery ( or battery connections ) isn't that great . Or possibly your field wire isn't in the greatest condition . Which would give your alternator a false reading . But that's rare for that to happen , but it has happened . I've rewired the charging system on my 79 . I run an 80 ( or is it a 95 ? I can't remember . tough getting old .lol ) with a yellow top and the factory gauge . I also have a volt meter but I still have wire it up . I run two 12" electric fans , a hot ignition system and a decent sound system and I can go out there now and check it at the back of the alternator on my truck and it will show 14 volts even with the big lumpy cam .