The Marantz integrated I'm sure will sound great. Probably not the amp to try to drive the Quads with though. I'm too late but I was going to suggest taking a look at the Cambridge Audio SR-20.

I like the Studios and although fairly efficient they do like some current, I'd only buy if you have a return option.

I don't know price and model by heart but I'd urge you to take a look at Golden Ear speakers who have been getting nothing but raves. They have both passive and some with amplified bass which would take some work off the Marantz and allow you to get the bass to your taste.

I personally would trust old amps over old speakers. Speaker surrounds rot and depending on environment some quicker than others.

You had some good choices on your list. I'm not a big fan of single driver speakers like the Tekton.