In Australia, you are best to get an A14, and if you already have the front mounted distributor in the ute, just switch over the engine. And enjoy the clearly better torque/power without the need for engineers certificate. If the A12 is good, do start with suspension.

You need to be sure the 1200 is what you want to spend your dollars on. Don't let your car be another of those 'unfinished projects' that you've paid the experts to half build for you.