If the tunnel is a standard Anschutz size (nominal 18mm thread diameter, 17mm-ish element diameter), other makes of the same size should fit. With metal elements you can file the lugs if these are too large.
Do remember than a lot of PH elements are smaller than Anschutz. I think they only made 18mm elements from the 1970s. Apertures might also be on the small size for current NSRA 10m targets.