bluetooth system for '62 Mercury

I have a 1962 Mercury Monterey that needs some sound. Currently only has the stock am radio with a single 6x9. I'd like to keep everything hidden (no new head unit). Basically what I want is a bluetooth (or aux cord) receiver that does audio out to a 4 channel amp going to 4 6x9's that ill have to mount somewhere. I use my phone for all my music anyways, dont listen to FM radio, and havent bought a cd in years. Do any of you guys know of something that would work?

https://www.amazon.com/HomeSpot-Waterproof-Bluetooth-Receiver-Motorcycles/dp/B019IIQCZG/ref=sr_1_1?ie=UTF8&qid=1472515626&sr=8-1&keywords=vehicle+bluetooth+receiver

Thats what i'm thinking of right now.