Well the MSD, the new one is OK. Fire comes in thru the bulkhead & the FL right there then goes inside & in/to/thru the ammeter then to a "welded splice" where it T's and splits & goes from there to the ign sw/some circuits in the fuse box/horn relay/headlight switch. I'd start from the back side of the bulkhead down to those areas searching for the open or opens