eBay 70's era 911 radio/cassette unit, OK for a 914? Options

[swm914]

I'm looking for a period correct radio for my 1974 914 and saw this on eBay. I though it was interesting because it is a neat looking radio and it has cassette as well. It was made in that time frame so the period is ok.

http://cgi.ebay.com/ebaymotors/ws/eBayISAP...0889&rd=1,1

However, I see three problems and wanted some advice. One, it may wind up going for more than I want to spend. We’ll see. I saw the same thing on a web site oldautoradio.com (any one familiar with them?) for $700. No way am I going there but their stuff seems over priced.

Two, it is described as 911 unit. I suppose dealers could've put anything into a 914 at a customer request (?) but would've this been to "high end" for a 914 in that time frame?

Three, it has a separate unit described to me as an amplifier OR something that is part of the radio reception?? I haven't determined yet if it is required for the unit to work or it is some kind of upgrade??? Anyone familiar? If the separate unit is needed, I don't know where it would go in the 914 without messing up the originality that I want to keep intact. I'm probably barking up the wrong tree here..

Any suggestions or advice appreciated. Thanks
Steve