Heck Dwight, that was quick! Thanks for the info mate. I've been looking around for either of the seats without belts, but as far as I can establish, the Cutting Edge items are no longer available. I'll keep looking though, as I'll need at least two for the Hasegawa kits.
I might be able to mould the main shell from plastic card, and then 'dress' the edges with stretched sprue or whatever. Second choice is to use a Matchbox seat, and try to make a mould to produce resin examples, but that could turn out expensive, in relation to a full cockpit set!
Oh, the joys of modelling!