Typically the Subaru wheels are in the +40 to +45 mm offset range, which is a bit on the high side for an A-body. With an 18" wheel and an 8" or 8.5" width it would work though, especially with a B-body rear although with those kinds of offsets a 68-70 would be better than the 65-67. It would depend on your exact wheel and brake combination but a small spacer may be necessary for some tire sizes. Other options for used wheels would be 350-370Z's, they have a bit less offset than the Subaru's. Or most modern Mustangs, although even the Mustangs start having a bit too much + offset when you get into the most recent body styles, especially the latest 5 years or so. Infiniti G35/37's work too.
I used to carry a 17" spare from a '07/08 Infiniti G35. I did need to do a little dremel work on the hub bore, it was a couple mm's too small. Not a big deal for a temporary spare though.
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The Enkei RPF1's that I run I had machined. They list the hub bore at 73.1 mm (which is a fairly standard bore for aftermarket wheels). That's actually big enough to clear the hubs on the later mopar disks, but, the RPF1's are pretty thin at the mounting surface, and the Mopar hub has to protrude through the wheel. The issue is that while the hub bore starts at 73.1, it tapers to a 65mm wheel cap. So I had my front wheels bored to 73.1mm all the way through at a machine shop. This was quite awhile ago but it was about $80 a wheel. For a small difference I wouldn't hesitate to do the work with a dremel (like I did with the G35 wheel), but for a significant change in bore diameter I'd have them machined.
You can see the difference in the bore here, stock
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vs machined all the way through
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The RPF's on my car are 18x9 +35 in the front and 18x10 +38 in the back, but that's with DoctorDiff 13" brakes in the front which widen the track about 5mm and a 68-70 B body rear axle with 1/2" offset springs.
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