Sell truck and buy new or old school:advise?

[Tim240Z]

Hi y'all,
I know that I am asking a biased group, but here goes anyways:
I have come to the point where I am looking to sell my 71 C20 to replace with a double cab or suburban. I love my truck and this is a very tough decision. I always thought I would keep it for ever, but my 6 year old son and I are going to start kart racing and the 3 of us (wife also) would need to be able to ride about 1.5 hours 1 way to the track. My truck would be a bit cramped. My dilemma is this: Should I get a new (06) double cab Chevy truck (about $25k), or get an older suburban (67-72)?
There are obvious pros and cons to each:

New truck:
Pros:
Nice and comfy with all the creature comforts and safety equipment (airbags, anti-lock etc)
Reliable
Space for 4 people
Good fuel mileage
Cons:
Emissions testing (limited mods, and I have a hard time leaving things alone)
Car payment
Extra insurance (due to car payment)
Dealership service for warranty integrity
Lack of real quality of new vehicles (our trucks were built to last)

Older Burb
Pros:
The obvious ones we all know and love, styling, classic, easy to work on, etc
no car payment
no extra insurance
no emission testing
Lots of space and can still be used as a truck to a certain degree
Cons:
Heavy and thirsty on fuel
old technology and almost a complete lack of safety equipment
Lots of work to get it up to snuff
Reliability won't be as good as new truck, not without a lot of work.

I found this one nearby:




Seller wants $2800. 4 Speed manual. I would likely do a 6.0L/4L80E swap (LSx)

This is what I would be replacing (71 C20 with L31 Vortec, 5.7L/4L60E)


or this: