Just realised yesterday what I wrote. Yes PH1 throttle into ph2.
Yes you could but it would put the management light on.
The fueling algorithm on the ph2 ECU relies on MAP as its main load so it would still run the engine ok, although if the resistance values of the TB are differnt it might adversely effect transient fuelling so it could end up slightly spluttery at small throttle openings, that could be re-calibrated in the map if you could be bothered to find where it was though.
So definately "possible" but probably not a great idea unless you are going aftermarket management anyway, or of course if you fitted the Ph1 ecu and UCH etc too, as then its essentially just the same as when people swap a ph2 dash onto a phase 1 so should still have working clocks etc.