Modern jump wings have the holes at 5cm (2" in old money). so you can set the jump at any height as per the BSJA heights i.e. 90cm, 1mtr, 1.05mtr etc. It really doesn't matter though, as long as the holes are drilled on each wing the same so you'll get the pole straight. Oh, normally the poles will be 10cm (4") thick.
I made 5 pairs of wings, a couple of gates, poles etc...... as you will be finding out, they aren't that expensive to make are they? It just takes a bit of time. It's the cups that are the most expensive item. Good Luck
Cheers, well just made a set for £22. Wood was free (offcuts that were going in skip), cups were £8.99 and two lengths of drainpipe came to less than £13. Now have a fully useable, upto 4' jump and will make more next weekend!
westgate are the cheapest for jump cups, you cant buy direct, but your local horsie place should be able to order them for you, think thay are around 5.45 per pair.