1972 Buick Electra Exhaust Options

Replaced the stock system with a Waldren Exhaust, stainless steel dual system manufactured to factory specs.
Looking to convert to an EFI system and want to replace the gas tank with a new one but nobody makes a replacement for the 1972 Electra. The closest to it is wider and would not fit between the stock resonators.
First mod was to replace the resonators with straight through pipe. Sounds 'sporty' but kind of loud for an Electra.
Put on a couple of Thrush Glasspack mufflers and I like the more muted sound and there is plenty of room for the new tank.