What speakers for Old school RF punch 45 in Xtra cab Pic included

First off let me say I have had this amp for since 1989 It pushed RF punch 10's and tweeters in a jeep. Well i have a extra cab truck with those little access areas behind the seat in the floor under those real comfortable jump seats lol. My problem is I have to put a wheelchair in that area behind the seat. I had to add to that area so wheelchair wheel wouldn't fall off area. There is about 9" on top added to that area and it is about 6" tall open on both ends. What size speakers do ya'll think i could add to the 6 speakers that are original. I would like a little more bass not nothing extreme were it shakes my neighbors house or anything some that will make it crisp and clear. I also just bought a Sony radio HU. with pre amp outlets, because original HU just plays radio nothing else apparently it was abused by previous owner of truck. Any imput would be appreciated.

Sittingbull2

 

Ya know a couple bucks down and you could get a much better amp. That thing puts out about the same power as your head unit. I don't know if it has some sentimental value but by todays standards its a little lacking in power. I used to have one though

With the amount of bass you'll need to keep up with the head unit, you're going to want a little bit bigger amp. Just a suggestion.