can this be done? 1963 impala upgrade

Good morning guys, I need a little help here - I've searched online and through our archives for some direction on this topic. Here's the situation... Customer has a 1963 Impala with factory OEM AM/FM radio. It uses a single (+) wire speaker output. The front speaker's negative is direct to chassis ground. The factory radio is rated for a 10-ohm load to the original front mono speaker. Here's the question: Customer brought a pair of Pioneer 4-ohm speakers to me to install in the front/rear speaker locations. Although I am fairly sure that an 8-ohm nominal load won't kill the OEM radio (wiring the pair of Pioneers in series), WILL THE SERIES WIRING / NEGATIVE TO CHASSIS GROUND cause a dead short or fry the radio? Basically, the flow would be like this: (+) out from radio to (+) of speaker 1, (-) of speaker 1 to (+) of speaker 2, (-) of speaker 2 back to radio and tied to ground. On my DMM, I still get an impedance of ~8 ohms when this is all hooked up (but not to the radio), but am I asking for a small puff o' smoke from the radio if I continue as described? Anyone with experience in these older radios, please chime in ASAP! Thanks!

It'll work.Support the12volt.com

Is this the same car we were talking about leaving the factory radio in and addin a new radio under the factory in this forum? anyway I wouldnt do it. the old radios are very weak. You can order a factory replacement 10ohm for that car Just like amps if you go below you will see smoke. Here was the other post https://www.the12volt.com/installbay/forum_posts.asp~TID~115126~PN~2

Hello, No, different post and OP. Customer is intent on using the original and fully-functioning radio - I just wanted to make sure that I was safely wiring up the new speakers correctly. Thank you for the quick responses. Erik Quick Mobile A/V Creations