Eeyore to get a transplant

[LMN8UR]

Here's a picture of my '72 back in 2001 shortly after I bought her. She looked Ok, but ran like well Eeyore "OK if I gotta" (Before I realized that it had a 2.76:1 rear).

The 2-bbl was worn plum out and ran real rich so my first project was to install an Edelbrock Performer intake, 600 carb, and HEI dizzy.

I traveled a lot for work back then, and I needed something a bit more dependable. My brother (a true professional mechanic) took Eeyore for a week and did this to her. Since 2001 this truck has been in every state east of the Mississippi excluding Maine and Wisconsin.

When gas peaked I replaced the old 3-speed with a NP-833 overdrive. Man that thing is sweet! Why more of you guys aren't doing that I'll never figure out! Plus Hooker headers an X-pipe and new 2.25 pipes.
Remember, I still have the 2.76 rear. . 65mph = 1400 rpm.

My brothers rebuild now has 175K miles on it, a couple weeks ago I kicked her in the butt and ever since then I've heard some unusual knocking coming from the engine.

I've moved out of Tennessee some time back, and left my mechanic behind. So I found a friend of a friend in Culpeper who has his own speed shop and I'm getting a 383 package rated at 410hp and 440 torque. I'm having him change a few things that will lower the hp, but pick up some torque.

QUESTIONS:
1. My current 168 tooth flywheel is drilled for an 11" clutch. Can I put a 12" clutch and flywheel under my existing bellhousing?
2. With my new horses under the hood and my extreme gearing, Who's man enough to see what the Eeyore on steroids will do top end? NOT ME ! ! !

Hope the picture come through. . .