You stated some goals of miliage and reliability.
The goal of achieving a low HP engine in favor of low speed Torque will make this an enjoyable engine package.
I myself would essentially build a Truck engine.
The 193 heads are an excellent street performance head that make UNREAL low speed throttle response.
A small bore 2 BBL intake off of a 283 would also work very well on the street.
I personally would use a stock 305 cam for the low base circle & tight overlap.
This will all make the engine run out of gas in the mid 4,000 range but will more than make up for any discrepentancy in high revs with OUTSTANDING low speed response, high vacum, & fuel effeciency.