1967 Formula S?? a find or not!

I found someone that that has three Barracudas. One is a 67 fastback formula S car w/o original engine. Now has 318 and auto. I think it has 8-3/4. Second is a 67 Notchback with 6 cyl pretty much bone stock with no options. The third is a 67 convertible. Engine has been changed to later small block. All are auto with steel wheels. Little rust in bottom of rear quarters. Stored in a basement and interiors are mouldy. But the cars are all there as it were. So the convertible and the formula S are not orginal anymore but they have not been messed with other than the engines. I did notice the Formula S fastback had the upgrade steering wheel and power drum brakes. None had air cond. Paint is still on all of them. Trying to get a ballpark idea of what cars like this are worth in todays market. I don't have any idea of which is more sought after. Seems like I have seen the fastbacks used as drag cars a lot. Are the notchbacks rare? What about convertibles? Thanks for any info.