If it was me I would do a compression check on that 383 or 400 in that 74ish truck you posted. If it checks out, grab the all of it, and slam it in there in one shot. That thing has just about everything you would need, mounts and all.
That wrecker is an interesting thing, motor looks to be about a 62 or 63 vintage 361 industrial motor, seeing as how its a two barrel low deck. A 413 would be an RB motor with a 4 barrel. Anyway, it does have the industrial manifolds that would fit the 361 motor that you are in love with (I am too). I am not sure they would fit the chassis though. You are in a better position to check than myself. The trans in that truck is likely a huge rock grinder thing that wouldn't fit under the floor in your truck and could weigh as much as the motor. While its cool, there aren't many parts on that truck that will help much.
Regarding big block mopar engine ID: There are two types, low deck or B motors and tall deck or RB motors. The 350-361-383-400 motors are all B motors and the 383RB-413-426-440 are all RB motors. I've added the 383RB in there, but it is a one or two year deal around 1959-1960.
There is no need to get casting numbers on mopar big blocks to get an ID, it is stamped onto a pad near the distributor. On RB motors the pad is on the top of the motor just behind the water pump, on the driver side. Its about 1"x2", level with the horizontal. On B motors the pad is just under the distributor, on the same plane as the passenger side head. The pad will have random things stamped in it, dates or other things, and the displacement. If the guy on the line was lazy he might have stamped in only the first two numbers, like 38 rather than 383 or 41 for 413.