DIY TIAL wastegate

just throwing this out for some flame fodder:
Looking at a TIAL wastegate and I find they are upwards of $700 for the larger ones. If I was to make one out of...(insert Sanford and Son theme)...a large exhaust valve, a slant six water neck and a wastegate valve actuator? The whole setup is an experiment on a dirt cheap diesel turbo setup for a junkyard 273. with no pressure the wastegate would pull valve up into 'seat' where the stat would rest. under boost, the valve would start to open, venting exhaust leg pressure out waterneck. Maybe get a matching valve seat and valve guide to make it more rigid? Flame on....