6.0/4l80 build opinions

[tmills213]

rookie here, would like opinions:

Current setup: 1970s block 383/th350 I bought from my friend who build it at school. It is probably 13 years old. I found it leaking from cyl 1 head gasket last year before storage. I could never get it running right with carb. My heart was in forced induction after by buddys grand national. I decided to go another route as well as gain a nice OD....

I currently have a donor 2500 and pulling the driveline. Its a 2002 6.0/4l80 with 317 heads and 200k miles. I got it for $1800 and am down to $1400 parting out so far. This is essentially a standard junkyard build. I've looked around but there weren't really answers why people chose what they did. Sorry if this is a no brainer, just delete it if it is.

Plans:
-new cam (heard gtm/ls9 is a good cheap solution but needs higher rpm for power?)
-plan on doing springs and going through valvetrain (no idea what exactly)
-ls9 multilayer head gasket
-flip manifolds
-turbo (not sure, gt45, t76...I have gathered around a 0.6# A/R ratio should spool fast enough for street. looking <$300? )
-transmission essentially stock, needs new rear seal.
-new T converter with what stall ?
-has 3.73 rear 14 bolt which needs posi/locker eventually
-stock bottom (hopefully solid when I check)

What do you all suggest for this setup.
It will be in my 1964 c20 and used for messing around town. No serious plans of racing it. I felt 600hp was not too far fetched for something I could comfortably take wherever I wanted reliably, am I insane?