Correct wheel offset and a happy front-end

[71beater]

I've been looking at wheels for my Dart... And it seems that people are willing to sell you anything close. What I want to know is, what is the correct offset?
I want to go with either 14 or 15x6 for the front.
I've got OEM 14" rallyes on it now, I think they're 5.5"... IIRC backspace is like 3-3/8 or 3-1/2.
I'm thinking my front end will be happiest with the offset being where Mopar wanted it, not plus or minus what somebody has in stock...
Of course out back is a whole 'nother story, but that can easily be figured out with a straight edge and scale.
Car info: 70 Dart,73 front end w/disc brakes. Will be skinnies like 195/70s.

Thanks Guys rayer:

 

[zhandfull]

Think your right on the stock Rally wheel being about about 3-3/8" B.S.
If your staying with 5-1/2" wide I would use the stock B.S. too at least on the front.

Or for 6" wide use a 3-5/8" B.S.

1/4" more or less B.S. probably no big deal on either wheel above on the front of an A body

 

[71beater]

Hey,
I'm pretty much on the same page as you brother...
What I'm really trying to figure is, what is really the correct number?
Just doing the math on that 5.5" wheel, I'm thinking the offset is around +10mm. If you look at re-pop 6" rallyes, they're typically at +6mm. Other wheels, companies like TireRack want to sell you with numbers nowhere near these.
I would think as long as I stay around that +6number I'll be fine.
Again, I'm just really curious as to what the original number truly is...

Thanks for your input.