If you don't switch to a split bowl you will have to buy a place diverter for an e pump. It can be done but they are a little more money. I am upgrading my e pump on my challenger to a split bowl.
Agreed. They make a diverter specifically for the JE pump, which IS what you have. They are a tad more money (like 35 bucks or something), but it retains the lo profile steering and F/R setup on your pump. IF you change to a split bowl, which can be done, easily enough, you just gained two more drain holes to plug on the lower starboard side of the pump where the cables used to come out, you will not be able to use them from that location with a split bowl. You will now have to drill new holes in the transom in the traditional locations for a traditional steering tube (Something new to buy) and the F/R cable and seal (Something else new to buy). Chances are both your cables will no longer work or be close to long enough.....soooooo, something MORE to buy, but those may need replacing on a boat that old anyway.
Worthwhile doing? Hard to say. Personally, I'd get it running, get it on the water and play with it. A Place Diverter will eliminate the need to be able to put wedges in, for the most part, and only some seat time will tell if a droop would be adventageous to your particular setup. Those are the only two real reasons to go to a split bowl in the first place.
The roost in this pic Brad took of my old 18' Sleek is a stock JE, AA impeller with and "E" place diverter. Probably a TAD more hp that you're talking, but I actually got it up higher than that later after some grinding and detailing.....

I beleive you can profit a good buck or two pawning off your old JetOVater ($200 is pretty cheap), get an E version Place Diverter (You never find them used, gonna hafta go new there, and your handle appears to be a stringer mount anyway, which you need a floor mount, or modify/make a bracket for that one). That one is also the older version Berk JetOvater, the newer Place ones do not have that reverse tube hanging down for one thing off the back which WILL slow you down, but rather have a flat pad on the bottom of them. The other difference is complicated, but to get that thing working, and it WILL work on a split bowl, there is about a $95 stoopid expensive super special seal you seem to be missing, and about $200 of other parts, some no longer made.
If later on you decide to go the split bowl route, your diverter can be retained buy picking up some traditional brackets from Place, or selling yours used (Should get a commanding price for it, since JE diverters used are so hard to find and yours will look new!) buying another since you've proven you can find good deals on them.

JMO
Ray
Oh, BTW, Love Sleeks! That's the first Sportster I've seen still retaining it's engine hatch!