Swapping masts and re-rigging

[mariner2k]

Will do. I have to remove the cobwebs from my geometry/algebra first.

The existing mast is rigged with a checkstay as opposed to a running backstay, going aft at a very shallow angle, propably not more than 10 degrees, about 2/3 up the mast. The old boat/ mast was rigged with a running backstay opposing a releasable inner forestay.
Given the shallow angle of the checkstay, how functional is it?