Stuck on engine direction

[analyte]

I'm really struggling right now with the engine choice. I have the following platform to build upon:

66 Chevelle
454 BBC w/ 357hp and 476tq at rear wheels
T56 w/ 3.73s
19in BBS RS-GTs
Ordered Kore3 C6 brackets for front and back
Will soon order SC&C Stage2+
Will soon order Currie upper and lower control arms
Will soon order Hellwig Pro-touring rear bar and front bar

I had planned to add Holley's HP efi with an Edelbrock Mini-ram EFI intake, but I'm looking at the price of EFI and comparing it to a 6.0 LSx. I'm sure I could sell off the BBC in pieces, but I'm not sure which direction to go.

I will take it to the strip at times, but I'm more interested now in running cones and maybe track days. I know the weight of the BBC is a factor, but the LSx has it's issue too I'm sure.

Has anyone swapped from a well-tuned BBC with EFI to a LSx with at least a cam upgrade? Did the mileage improve (I get around 15-16 on the highway currently with the OD)? What about driveability withe a stick as the T56 limits my choice if I want good street manners at low speeds.

BTW, my budget is around $4500 to get it in the car if I go LSx stock as I want to drive it this summer. Mods such as cam, etc will come later. With long block 6.0s going for around $1000 in my area, that leaves about $3500 for LS1 intake, ECU, harness, etc.

Thanks,
Kerry

[ErikLS2]

I haven't swapped a BBC for an LS motor but it seems like a no brainer to me to go that route. I would advertise the BBC for sale as a complete engine that you can hear run in the car and even drive, and then pull it for the buyer. I got like $850 for the 327 (already removed) out of my car that I had no information on other than the guy I got the car from had "gone through it". IMHO I can't imagine why anyone with all the other PT stuff you already got on the car wouldn'tgo with an LS motor. Good luck!

[parsonsj]

Has anyone swapped from a well-tuned BBC with EFI to a LSx with at least a cam upgrade? Fellow moderator Andrew Borodin did exactly that:

https://www.pro-touring.com/showthread.php?40904-1970-GTO-Version-2.0

[analyte]

Thanks! I'll ask Andrew how the mileage and manners changed since he's also running a stick.

[Chevy406]

Fuel mileage will jump up at least 10 mpg (you will see mid 20's cruising on the interstate). Drivabililty with a stock GenIII will be pretty much like a modern car. Even with a modified GenIII/IV with heads, cam, intake, exhaust you can have both your cake and eat it - but you will be at the mercy of your tuner's abilities. I have my daily driver '99 Corvette almost stock like but with 470 rwhp after playing around with HPTuners for the past year or so.
You will easily improve the 357 hp of your currenty engine by swapping to an LSx. The wow factor between a BBC and an LSx is a question that only you can answer. I recently faced the same turning point in my build, and I ended up shelving my Dart SBC in favor of a building a 6.0 liter. It was simply time for me to ditch the carb.