This is from a feeble memory, so it's worth what you pay for it.  My recollection is the Super and 9mm's have a slightly more narrow barrel hood.

But if you're looking to turn a .45 ACP gun into a .38 Super, you might want to think again.  The .45 ACP and 9mm/38 Super/40/10mm frames are different in the feed ramp.  The .38 Super barrel throat will most likely slightly over-hang a .45 ACP feed ramp since the .45's feed ramp is cut deeper than the 9mm/38 Super/40/10mm frames.

If you want to swap from the 9mm/40 family of cartridges to the .45 family, you'll need to mill out the feed ramp and use ramped barrels.  Otherwise, have a dedicated frame for the .45 family, and a dedicated frame for the smaller cartridges.  

Frame was listed as 9mm 45 frame, I want to keep it as 38super pistol. My problem is that when buying 38 super slide and or frame the hood extension width is not specified. I sent email to Fusion Arms and got response that this dimension is .373-.375 on theirs slides. I have Colt 38super barrel so when the frame is shipped I will put it on the frame with the slide stop pin and see how the ramp looks like and go from there. My hood extension of SA Target in 38 super is wider than that on Colt barrel so that's why I was worried about this. Thanks for the response

I just checked a switch top 1911.
Barrels are ramped Nowlin.
.45 ACP slide is SI stock that came with the gun. Around 0.436 wide hood slot.

.38 Super slide is a Nowlin after market.
Around 0.367 wide hood slot.

The ejector required slight alteration to work with both slides.

Both are completely reliable with ball or SWC.
.38 Super needs pretty tough SWC even in the discharge machined (mirror finish) Nowlin barrel to prevent leading.

It really freaks folks on the line out when you switch from .45 boom to .38 Super crack in less than 30 seconds.