Your engine was made on 23 February 1982, so it should have a very early Magnetron ignition as far as I know (I don't know the exact date of the changeover).
If the drive belt cover screws are cheese-head you can usually grip the outside of them with vicegrips and undo them that way. If they are roundhead you are out of luck. I'd probably try to undo them with a punch (center punch or cold chisel) on the outermost part, working on opposite sides for successive taps. It usually works, and if it doesn't, you still have to cut the heads off them, which you would have done anyway.
It sounds like you have been extremely lucky to get that mower. I don't recall whether the catcher was the steel-base canvas type - if it was you can probably make one fairly easily, but for such a good mower it would be much better to have an original one, at least for show (you might use a rougher one in practice for everyday mowing - canvas catchers are not very durable).
