The ring gear is unique to 454 so if the engine doesn't have one, you'll need that. The starter will fit from a small block as long as it was a small block with the large flywheel.

Motor mounts bolt on from a small block. I did that in my 66 GP automatic car and it worked fine using them.

I have put big blocks in to replace small blocks and never upgraded the rad but you won't know until you try it.

Pulleys and brackets are all 454 unique as you likely already know.

I did this swap in 2006, but I went with a turbo 400.

1.  I used the same motor mount towers that are bolted to the undercarraige.

2.  Motor mounts are the same as a small block.

3.  Engine harness is different, as the oil pressure sending unit wire moves to the drivers side of the firewall gutter, and the wire needs to be long enough to reach down to the sending unit.   TCS Solenoid also is in a different spot, but I suspect you'll be scrapping that.  I've seen a few variations re water temp wiring on 70 350 cars, proper place on 454 is on drivers side head.

4.  Make sure you radiator is big enough.   I started off with a 3 core big block unit (shared the same shroud as a 2 core big block item) and needed to increase to a 4 core rad.  It required a unique shroud.

5.  You'll likely need to change the front coil springs as the big block will drop the nose. 

6.  Big block power steering pump is different, the inlet is on the side, instead of the back like on a small block.  (you can likely use the small block on however).

7.  Alternator & power steering pump brackets are unique to big block.

8.  Alternator, water pump & power steering pump pulleys from 70 350 will work with big block, but different crank pulley is required. 

9.  You will require an externally balance large flex plate, and the starter for the large flex plate.

-- Edited by seventy2plus2 on Sunday 27th of March 2011 10:46:51 AM

The flywheel from a 400 sb will work as well as they are both externally balanced.They are the only 2 chevy motors that share such pieces.The front bracketry depends on left hand or right hand alternator/short or long water pump.I am currently using my power steering pump from my '81 Z/28.I had power steering lines made up(NAPA/Auto Value).I also used Moroso solid motor motor mounts on the original frame mounts in the car.Just to make sure that a rubber mount is used on the tranny to absorb the energy.I might even have a brand new Z bar and clutch fork laying around her somewhere.Depending on what you are using for a bell housing depends on where the pivot ball mounts-block or bell housing.I have a scattershield w/ block saver plate and my pivot ball is on the scattershield.If using headers don't use anything bigger than 1 7/8 tubes as you'll need clearance for the power steering box.I don't know if the boxes where moved up front in that year or not.Oh and DON'T forget the pilot bushing in the end of the crank!And there really is a difference between a auto starter and a 4 speed starter.The 4 speed starter has a smaller cone.I went through this a while back.And some starters have offset holes so beware.I have a collection of them on my floor-offset and straight across including one from a 375 hp 396 circa '68. I hope this helps.PM me with your wish list and I'll see what I can do to help out.

Another thing to check Steve is oil pan clearance, depending on what pan you have, it can come in contact with the center link when turned all the way left or right. I had to massage the front edge of my chevelle pan for clearance on the 65. My big block is still in the corner awaiting an injection of money.