That would be my choice too - any old 4.3 or 350 Chevy C/K, any age. They did sell some with the 305, but not sure if they’re desirable… they maybe the economy of the 8 with the power of the 6 type deal…
Or else a Dodge Ram. I know they can run the distance and still work great in the 94+ version. I don’t know much about the pre-94 dodge rams, but have always liked them and wanted one.
I’ve seen the pre-94 dodge trucks, including some with the slant 6, for really cheap.
I've had a GMT400 305. It was totally fine. Enjoyable to drive around town even when slightly loaded up although it ran out of steam on the highway noticeably quicker than 350 GMT400s. Fuel economy was marginally better, really a minimal difference. I'm not surprised the 350 was so popular... 305 was pretty much pointless. But not bad and thanks to being "undesirable" you can get a deal sometimes.