Ron,

I can't say it's true beyond a doubt, but I've heard from any number of sources that RTV outgasses some sort of corrosive stuff. Most lately, I was warned by a lighting expert not to use clear RTV to seal a crack in a headlamp lens, as the gasses would eventually attack the mirror coating on the reflector.

I can say from personal experience that RTV is not long lasting as a sealant when exposed to the elements -- lasts maybe a year and then starts to peel. This surprised me, as I've used quite a lot of the stuff in aerospace, but those items required periodic servicing so the RTV had to come off anyway before longevity became an issue.

I use marine epoxy on soft plugs in the block, but haven't found it necessary for plugging injector holes. Wouldn't hurt anything in most cases, but if Chris is contemplating going back to EFI eventually, it'll make it tougher to get the plugs out again.