5 1/4s eh? Hmmmm.. I was thinking components too - I had components in Betsy I, back in the day (95) and haven't had the same clarity since...

As far as the dash spkrs, I'm taking the ones from Betsy IV to put in Betsy V, so they'll cost nothing - they're Kickers, and with bass caps they'll do okay filling in the sound - as far as the load, I'm not too concerned since I have an amp: thinking I'll use the head unit for the front dash spkrs, the head's rear output for the doors, and an amp for the rears....I think. So no go on the 6 1/2s eh? 6x9s definitely fit the rear?

1991 HZJ77, 1999 KZJ90, 1999 UZJ100, 1992 M101CDN2
https://www.thegearheadproject.com/category/jdm-journeys/