Anyone had any experience using them on steel rims?
I reckon there's about 30mm+ space between tyre wall and wing so plenty of space.
Could always go for wider wheels/tyres, but increasing the track slightly would make it easier to straddle all the speed bumps round here!
The early 4 bolt wheels you'll have on your 72 have a PCD that's not really that common. The Rostyle wheels for instance Morgan borrowed from an early VW Beetle.... the 5.5 inch width 15" wheels coming from a reasonably rare South African Beetle model.
I would advocate getting a set of the right wheels rather than fit spacers.
btw - when over tyring a 4/4 the measurement to check is the distance between the inner/upper of the front tyre and the top cross head mount. That'll be the place it hits first. You can quite easily over tyre the rear (I run 205/55/15 on my '72 2 seater) but a narrower 195/50/15 on the front.
I have genuine Minilite wheels 5.5" x 15" running a standard off-set matching the Rostyle wheel (which is the maximum Minilite can machine on this particular casting). You may be able to get more dishing if you used Image wheels and accepted the 3 piece modular design and the rim bolts that this results in.
I have a spare set of Rostyles and various Yokohama AD08's in the necessary sizes (or Toyo T1R's in 185/55/15's) if you are interested.