Wheels on '73 GT Junior

[f1worldchamp]

Hi guys
I've checked through other threads without much luck, so I hope someone can help.
I already have in my possesion a set of alloy wheels I'd love to put on the GTJ. They are 15x7 and 4x108 PCD.

A) The centre bore is only 57mm, can I assume these can be bored out to 70mm to suit the Alfa hub?
B) The offset is 37mm, which seems a lot larger than the wheels I've seen recommended where I think 30mm was the largest. How much of an issue would that be? Should I be looking at a 7mm spacer to compensate?

Thanks in advance!