no need to guess Stuart! we know yer right .... there isn't a deco 4 speed that doesn't require double clutching to down shift, and the more they've been abused in their long life, the more they need it
the basics, Chad: clutch in, slip trans to neutral, quickly let clutch out, tap gas to rev engine, quickly clutch in, downshift, apply a bit of gas as you let the clutch out again - takes practice, and the non-syncro trannys work better double clutching on upshift too, slightly different sequence
and welcome to the shop, that's one nice lookin rig you've got
Bill