Vortec 6.0 detectives?

[50 Chevy LS3]

Just purchased a 6.0 Vortec engine from a salvage yard. The yard owner said it was pulled from a Cadillac Escalade, from another yard and swapped to him for a Corvette project of his own. He decided to go with a alum. block 5.3, so, this is the reason I got it. Engine is complete except for starter, alt., and acc. pedal. Engine wiring harness is there but, not very good.
To confirm it is a LQ9, we bore-scoped a cylinder, and it has flat top pistons.
The junk yard guy said he did not know miles, or year, but thought 2003.
It has the 317 heads, and I plan on pulling them for a re-work and also checking the rods and mains. Here is a picture of the pcm serial number.

Here's the questions:
1. Does the computer numbers tell anything about the engine or year of mfg.?
2. Is this computer a good choice for re-programming?
3. Does anyone have a good recipe for budget 400HP LQ9? Will have to use block-hugger headers.
4. Without a vehicle VIN or year, is it going to be hard to get the correct acc. pedal?
I'm sure there will be more questions, but, hope you all can answer these first.
Thanks.