[3QTRTONS]

....Scosche makes an underdash stereo mount that'd probably work for what you want to do. 'Google' that name to get locations & prices. I saw it offered by WalMart for $14.88 & I'm sure you could get it elsewhere for similar money. JMO, but the front dash speaker replacement is a PAIN! Your idea for 6x9 boxes is a good one; or you can acquire a pair of OE metal frames and insert some NICE sounding modern 4x10 speakers into the cab corners - which was not unusual to see as an option in that era. No matter what, I wouldn't want a floor console getting in the way of my Honey's legs, or whatever......