Boost is the easiest way to make power thats for sure with the tough A series internals its a great base. Stock A15 are perfect and all A series have very thick rings.

I wouldnt be stroking an A15 anymore thats why I mentioned big bore 83.5mm as a choice as the A series has more block integrity than an L series which has been sleeved in the same way thanks to shorter pushrod layout.

The advantage of 300cc extra is you can make use of the L series valves which can fit say 40mm by 33mm which is ample for 1800cc (a14 force has 42mm inlets!). In Japan many A15 bored to 1600cc using big ports, valves and the best goodies are revving to 10,000rpm making power I have an article in japanese somewhere hopefully can find it about a group of 1200 ute owners showing how to build A15 for this duty. Lower that rpm to 8000 by adding 300cc more and even down to 7000 with boost.

A h89 A series head has good flow compare to many other 1.8L 8v engines and with the valves mentioned above and 1800cc would be an awesome setup using custom manifolds, ca18det efi bits with nistune ecu.

The block will not be an issue with JB welded sleeves, grouted to welsh plugs, custom mains bearing brace, prepped ca18de rods (they fit by shaving sides a tad) and I would like to go this way providing 2 things - I can get a 71 series box behind it and then an 83.5mm head gasket carefully calculated for the best cylinder offsetting.