Question about my non original slant six

dustyaman said
I have a 1975 dodge dart with a slant 6. Yesterday I checked the cast numbers and they came up as a 1968-70 cast slant 6.

Not quite. 2806830 is the casting number for a '68-'76 forged-crank RG block.

Now my question is since in 1975 the slant 6 went down 90 hp and the 68-70 the slant was rated 145 hp is there anything different between the blocks

No difference in the blocks.

or is it all smog equipment that drug the hp down?

That's part of it. It's more complex than just that, or just a change in the rating system. See here.

The slant has a external fuel pump that makes it easy to start up

Er-ruh…whut? Does not compute.

What is the engine ID number (stamped on the block deck surface, below the front spark plug, just inboard of the base of the alternator/coil bracket...you may have to clean away some grease to read it)?