Moving a '68 427 4 bolt block to a 454. 4 speed.

What casting numbers can I look for to make sure I'm getting what I need? (I know I can't use my 396 flywheel due to internal/external balance deal.)

Will I run into any starter problems?

Thanks for any help.

go here... http://www.gmpartsdirect.com/

I got one for my 454 here for $178 +/-

It will be externally balanced 168 tooth and you will need to match the starter (gear) to the flywheel (gear)

For used the only number I know is Casting #3993457N for the 454

Flye,
I'm at work now, but that number posted by Stano is the number which I remember seeing on the 454 flywheels which I have under the workbench (if you want confirmation, I can look when I get home tonight). Almost everytime I go to the swap meet, I see at least ONE 454 flywheel for sale for less than $50. They are IMMEDIATELY identified by just looking on the front side (engine side) for that extra weight. BOTH the SB400 and 454 require the UNbalanced style flywheel. IT IS EXTREMELY unlikely that you will ever run across a SB400 flywheel for a manual tranny. MOST people who build SB400s and 454s have them balanced by the machine shop and the 454 flywheel with the added weight works fine for building either engine.

I'm home now, and yep, all the 454 flywheels that I have under the workbench are 457N.

I've heard there's a bolt-on counterweight available for internal balance BB flywheels (like 396-427) to make them compatible with the external balance 454 crank. Does anyone know if this is OK for performance use?

Yes and Yes, but, I personally don't like it.
First of all, since it does go between the crank and flywheel, that means that the flywheel is about .120 (thickness of the counterweight) further AWAY from the starter, thus the starter drive doesn't engage as much of the teeth on the flywheel.
Apparently many of these are sold and used, and I have installed them on a few of the engines which I have built for people. Quite honestly, I have never heard a complaint about one.
If an UNbalanced flywheel is unavailable, my preference is to use a big, 168 tooth neutral balance flywheel and have metal removed from one side to provide the necessary balance. I have also had this done for people as well as have one like this on my 56 Vette with a SB400.

Thanks Tom. I bought a 454 engine I plan to build next year. It came with the harmonic balancer but needs a manual trans flywheel to work in my car. I'll keep my eyes open at swap meets for a 457N.