Please excuse my Ignorance, this is all new to me...but I'm really starting to enjoy it.

I inherited this '79 Shortbed from my Dad, it was his love and pride.
Years ago he had it lowered a bit and I'm wondering what kind of drop this is?
I have a LMC Truck catalog and it shows stock rear height should be 34", front 32".
My truck measures 28" rear & 27" front from the ground to the bottom of the wheel arch.
It also shows at this height the tires should be tucked under the fender, mine does not.
I will be buying new 20" rims and tires and was hoping they would tuck under for that slam look.
Oh the lowering parts that are in it does say Bell Tech if that helps any.
Thanks.