Tom, I used the Kirkham FAQ for all my BH/FW/Clutch parts. See:
KMS FAQ
The Mcleod 563210 has billet alum body, with steel friction surface (rebuildable) and steel 184 tooth starter ring:
McLeod Racing - Aluminum Flywheels
Your pinion engagement of 2/3 to 3/4 ought to be enough if you are using the correct starter for the 184 tooth FW. I use the Tilton 54-20013 Severe Duty Super Starter. I can't say how many teeth it has, as it is not possible to see the pinion with it in the car. Do not use the supplied shim between the face plate of the starter and the starter body. If you don't use this Tilton, then make sure you use a starter for the FE and not the FT or 429/460 motor. They have different FW sizes and tooth counts.
Sam