BAh, Find a straight Chassis on a car you love. Numbers be damned. The Fossils are not about practicality and unless your looking to spend $40-50k and store it in a climate controlled environ? I'd say to hell with it. Find a car that does it for ya, just makes the heart flutter. Buy it, live happily ever after.
Just like a lot of ugly women out there. Somebody loves em' enough that they don't even notice the bondo or a sagging quarter panel. See if you find a straight chassis but maybe not a Matching Numbers chassis then you are going to pay a good bit less, and you end up with a car you enjoy but aren't afraid to drive. Win-Win unless you are a serious collecter.
Also Dazz, Bro of mine In Kuwait right now, he's come across a whole bunch of cherrie old scholl detroit iron. Might be fairly easy for you to get hold of in Ireland.
As for MOPAR, I love em' had a 1971 Plymouth Valiant Scamp, with a 340 in it that was a holy terror. The little A-bodies are seriously lightweight, and when you throw a proper 340 in em' are just rockets.
But, if I was going to build something today? It would probably be either an older 62 Buick or a 67 Thunderbird. Then just have fun with em'.
Then again there is a lot to be said for sticking with a good old generic Chevy. Cheap and plentiful parts, run just fine.