72 K10 Help me decide...Fitech or 6.0 swap

[suburban99]

Hey all. Help me decide if I should keep my existing 350 and just add Fuel Injection or swap it for a 6.0 LQ4 that I bought a few months ago.

72 K10 4 inch lift on 35's.
350 has been rebuilt with few miles on it, as has TH350.
HEI large cap dizzy.
The engine has a sticker on it so I called them to see if it's the original rebuilt or a drop in. They didn't have records back to 2004 when engine was installed.
Hard to start when cold, idles like crap until warm then not great. Does not leak oil or burn oil.
Truck drives excellent on the highway, no vibrations, 70 mph without an issue.
Drove it over the Coquihalla highway (highway thru hell) in a blizzard last week.
It's like a 7-8% grade for several miles tops out at about 4000 feet...pulled the hill great..shifted into 2nd gear at the very top at 50 mph.
4x4 works perfect with no vibrations.



The LQ4 I removed from a 2002 2500HD 4x4 with 240,000km (150,000 miles)
Ran good no knocks but 4L80E was toast so I did not drive it.
I repinned the harness for stand alone and bought a reprogrammed ECM from a vendor here.
I have modded the flex plate to accept the TH350.
I am into the motor for about $1000, but can easily sell it or put it elsewhere
(I have swapped a 5.3/4L60e into a '62 C10 a few years back)

Dual exhaust needs replacing and the exhaust manifold donuts last about 2 weeks...
I just can't decide whether it's worth the hassle to take a great running engine out and swap in a LQ4.

Currently gets about 14 mpg on the highway...

This is a spare truck for me and my family, hey Dad can a borrow the truck? So it needs to start, run and drive good.
I really like the Fitech and have read some good things about it here and elsewhere. My current carb needs to be replaced as it was just rebuilt and is leaking air through the rod holes (worn)