Yeah just shaving the door handles would look strange with the belt-line molding in place - unless you somehow just extended the belt line to make up for it. Then it would seem like a waste of time just to have the exact same look.
People have removed their entire belt line moldings from a stock body before and there are pics on the forum. It is a WHOLE lot of work though. Remember too the belt-line serves as a means by which to actually secure the body panels to the chassis, so if you fill it in it will be very difficult to perform body work should a panel become damaged.
I'm building a 246GT Dino replica and I've removed the door handle and lock from the outside. I've put in the solenoids and the "popper". I have a bunch of pictures of how I did it and I'll post them. Mounting the solenoid so it didn't interfere with the window was the biggest problem. I'm using the remote, so I won't have a button mounted anywhere. I do have a hidden cable release, but I'm not going to post about that!
Fieros look fine without doorhandles and belt line trim left alone. As far as getting a pop door to pop open... Where the door meets the rear quater there is a half inch over hang and the steel behind it is hollow and easily accessible. Where the white rectangle is, thats where the popper will sit, behind the metal and held on via a l bracket and pop rivets. You could spot weld and then blend it back for a smoother look. This will be to pop the door out. You need to trim the plastic on the body panel where the lip is to allow the plunger to extend out of actuator. This can be as small as an 1/8 inch hole or you can us a half inch square driver and 2 part epoxy the body plastic onto the face of the plunger for a smoother look. If done right you cant tell its even there.
Another pic of a fiero with no door handles and belt line
When I was in my younger days, I also installed such a kit on a Nova. I had alot of problems with it, and if I did it differently I would have a manual release cable (NOT electric) probally mounted in the drivers side wheel well. *You need to be able to work the latch with the cable, not the striker.
It's a lot of body work to remove the belt line. Be prepared for that. And removing your body panels are going to be more difficult, but not impossible. I can still remove my door skins and front and rear fascia. The front fenders had to be cut off when I added vertical doors, but they were bonded back on okay. The rear clip can't be easily removed, but that's true for 99% of the cars on the road, so it's no big deal.