OK, let's try to get to the bottom of this once and for all! I've done about as much research as you can do on this issue. So here's what I came up with. In the end, we're screwed with regard to our options, but it is what it is!

SERK 3/4 Tires:
Front:
The SERK 3 came with Dunlop Elite 3 or HD Dunlop D418F, 130/70 R 18 M/C 63H, H speed rating, 600lb load rating.
The SERK 4 came with HD Dunlop D407F, 130/70 R 18 M/C 63V, V rated, 600lb load rating.
Rear:
The SERK 3 & 4 both came with HD Dunlop D407, 170/60 R 17 M/C 78H, H speed rating, 937 lb load rating.
The rear tire is still available as originally released for these bikes, only from HD, and I think it's a pretty decent tire. The front tire has been changed to the SERK 4's tire only, the D407F, which I happen to think sucks, even though it's a V speed rated tire vs. the E3 H rated tire.
Now I've checked with Avon, Metzler, Michelin, Bridgestone, and Pirelli. Not one of these manufacturers makes tires to match the specs of our bike's tires!

Metzler's the only one close. The ME880 comes in a 130/70 R 18 M/C 63H TL, which matches our front tire specs. But they only offer a 170/60 R 17 M/C 72V TL for the rear. It's a V speed rating, but only a 783 lb load rating! That's giving up 154 lbs of load handling capacity in the rear! Seems like too much to me!
No other vendor even comes close to the right sizes and load ratings for our bike's tires!
So it appears that we need to stay with the HD supplied Dunlop D407 rear tire.
But according to Dunlop's site, they make an Elite 3 for the front. It's a Dunlop# 4080-78, Elite 3 130/70 R 18 M/C 63H. If that tire is available directly from Dunlop, it seems to be the best choice for the front.
I don't believe in mixing tire brands and/or styles. I also don't want to give up over 150 lbs of load handling capacity. So I'd probably wind up staying with the Dunlops. But I hate that D407F. Would anyone mix a Metzler ME880 front with the Dunlop D407 rear? Has anyone obtained a Dunlop Elite 3 instead of going to Harley for a front tire? Is that Dunlop E3 tire even still available? I'm not liking our options here and hope the Elite 3 front might still be available to us thru Dunlop. What did ya'll find on your ends?
P.S.: If you find an alternate tire, please post the specs for it. (full sidewall number).
Hoist!

*Corrected front tire models