Personally I would be tempted to ask Aptec if they could hone out your current plate, relieve that exhaust bridge back a tad and match to an OEM piston.

The extra postage to Ireland is worth it for those miles of green country roads and rivers of proper Guinness though eh?!?

Note: might be worth talking to them about the skimming of the head surface as well, most platers tend to do this as a matter of course, but if yours has just been done and it is square it would be a shame to loose metal (port timing and squish) for nothing.