Measured the 300 flywheel I have (saved for a future project!)
It's 13.5" diameter with the ring gear. 160 teeth. Same as the Buick 350.
Looks like the Luk LF131 is 153 teeth and 12-7/8" in diameter.
I 'think' it will bolt up to the crank, but the smaller diameter means the starter won't engage it.
A Buick V6 flywheel could fit, but it's heavier and the balance is wrong. Could be machined to work, but that'll cost ya.
Brian had posted about it in the past. Maybe he'll chime in.
TA Performance has new billet flywheels, but they're $315.
Best bet is to look for a Buick 300, 340, or 350 flywheel. A Jeep with a Buick engine is another option.
On my '66 300 engine, I used a '66 V6 bellhousing and a 350 flywheel.
V6 and V8 bellhousings are the same on the early cars. Later 350,400, and 455 ones will work too. Some fit other makes and have provisions (bump outs) for starter on left or right side.
The Richmond 'street' 5 speed I used bolts right up to the combo I have on my '66 Special. It's an extra low 1st gear (3.26 ratio) and a 1:1 5th gear. Works well with a rear in the 2.79- 3.08 range.
