Greetings,
I know this is an old post but got some info on the Iron Duke... I built one up in the mid 70's and got about 200 hp out of it with some minor mods. I bored it .125 over, from 3.875 to 4.000, and used 4 inch flat top pistons from a stock 327 Chevy, reworked the head, clearanced the crank, put in an Isky 232 cam, had a custom-built intake designed around a tunnel ram for a small block Chevy with a reworked Holley 500cfm two barrel, dual point distributor and a header. It was a sweet running engine... The engine was built by a guy in Albuquerque that built circle track cars. Some other additions I wanted to but didn't get to were roller rockers, high volume oil pump, electric fan, MSD ignition... and a few more things to get some more giddyup out out of it... For a four cylinder, it had quite a bit snort... Anyway to answer some other questions, the front axle will need a new mount. The older four cylinders had the intake on the drivers side which may have some interference problems with the front driveshaft and I'm not sure about the transmission/bell housing bolt up to the Eagle drivetrain. There are some good books out there on how to build up the Chevy six cylinders which are basically the same as the fours minus two cylinders. There's my two cents worth on the subject.... Questions??? Ask away... I've got six Eagles, wags, SX/4s and a Kammback, I've been playing with for years... Have an Eagle day... :0)