Stewart....
Swirl port heads are restrictive... Find the Even-firing three liter as fitted to Eagle Premier/Dodge Monaco from '88-'91(?)... I forget years of model range. Late engines got a water pump without the elbow hoses. They all got 'E' heads so much improved intake flow, a bigger oil pump, hydraulic lash adjusters and tame cam profiles. Give this one modest boost with plenty of attention paid to engine management and you may even be able to avoid breaking a ring land. When that happens give it forged pistons, H-beam rods and it will be good to go. Want to get really silly? I've stroked the crankshaft for a nice runner.