I'm thinking new barrel and mags. Am I correct, or is there more that needs to be done?  THANKS!!

I'm not a gunsmith but both of my old raceguns were 9mm's before they became  .38 supers.  I think you're mostly right but you may have to tweak the extractor a bit and might have to open the breach face some on some guns.

.

barrel and mags maybe recoil spring and extractor

go with 9x21 and keep the 9mm barrel and spring then  you can plink on the cheap

check to see if you need a ramped or non-ramped barrel. That's about the only significant difference. Unless you're wanting to shoot PPC with it, a roto barrel from sarco will work (non-ramped) http://www.e-sarcoinc.com/9mm1911barrel5roto.aspx

if you want to do something nicer this Ed Brown would work http://www.brownells.com/handgun-parts/barrel-parts/barrels/1911-drop-in-match-barrels-9mm-prod85741.aspx?avs%7cMake~~Model_1=1911__5%22

I've got a non-ramped springfield 9mm that a used colt 38s barrel dropped into with no gunsmithing and a kimber 38S that a SA 9mm (ramped) dropped into. I bought both of these barrels used for less than 75 each.

for mags, I reload my 9mm at max length and have not had a problem using 38S mags in both of my 9mms, although they are range toys.

hth

All you need is a barrel and magazines.  You can change the recoil spring if you want, but these days there isn't a ton of difference between 9mm and .38 super, so chances are your 9mm recoil spring is just fine.  No you don't have to change the extractor, and chances are you won't even have to adjust it...but if it's on the heavy side tension wise, then .38 Super will be even tighter.  But chances are your extractor will be just fine.

There is no opening up of the breech face, 9mm and .38 Super are the exact same slide; so no worried there.  This is a REALLY easy thing to do.  

Fixed it for you.  You will need a heavier recoil spring, (probably 16#), and a shorter ejector.  These days I shoot more .38 Super, but if high velocity is your goal, the 9x23 mm Winchester is the way to get it.  Brass is a bit rare, but not so bad when compared to 9x21.

9x19 FMJ will usually work just fine through 38 Super magazines even with the shorter ejector.  I have not had any problems, but for serious use I go back to either 9x23 or .38 Super barrel.