I saw where you was talking about the vintage 30's being good with mesa they are real good but I have found a cheaper speaker that sounds just as good has all the same specks not sure if you heard of them but might want to check them out they are at
www.warehousespeakers.com this is what is said about them there.
12” Veteran 30™ speaker - 60 watts
The 12” Veteran 30™ speaker from Warehouse Guitar Speakers, LLC is tonally superior to Celestion's™ Vintage 30™ speaker. The tonal improvement is in the upper-mids. The Veteran 30™ speaker has smoothed out the upper-mid "spike" notorious in the Vintage 30™ speaker.
Drop in replacement for Celestion™ Vintage 30™.
Harmony central has some reviews on them as well and they all seem to be good.