This a Good Online Magnum Deal?

I have to agree with the above if you can do it.
Look for a wrecked truck and use some of the money you save for some CH318B Engine Quest heads and your cam set up.
The CH318B heads have the intake bolt arrangement like the LA motors have so you can use any small block intake you like instead of being chained to one choice of expensive Chinese intake.
The bottom ends of the magnums are pretty tough and stand up well, but the OE heads generally have valve and seat issues earlier on in the mileage.
I paid 500 delivered for my long block with 96k on it, and even though the bottom end bearings looked really nice and the cylinders had very visible cross hatching still in them I could see daylight between some of the valves and seats.

Normally the EQ heads come with 1.92 intake valves, but those can be replaced with 2.02 valves if you think you need them.