The current piston used in a deluxe I believe is slightly domed.
A domed piston will increase compression but at the same time it will also increase the weight as a domed piston is heavier than a flat head (you need the reciprocating assembly lighter) the increase in compression might also need higher octane petrol meaning the engine might knock on regular supreme petrol.
Then the Quench (Distance from the piston top to valve) will also need to be measured with clay to make sure the new domed piston does not hit the head.
There are other alternatives when it comes to increasing compression, i.e. thinner head gasket, milling the head or cylinder deck etc. Compatible pistons might be available but one might face difficulty finding the exact same sized full domed piston to fit in the current bore without any bore increase taking place.