One thing you could ask yourself is, what are my goals for this bike ?? If your goal is show room quality, and it needs a repaint to attain that, $150 is too much (think $550 - $600 when you get done). If your goal is show room quality and many parts were changed or are worn, $150 is too much (think $300 - $400 when you get done). If you goal is to have something fun to ride (don't look down, it looks awful down there), $150 is too much (look for something sprayed rattle-can black for $50). If your goal is a nice bike in nice condition to make friends envious and make you feel good when you ride it, $150 might be darned cheap.
In questions of this type, it's good to consider opportunity cost. How many have you seen for sale in better condition ?? Do you know how to do a "completed items sale" search on ebay to get prices on similar itemsa ?? How much would it cost to have one refinished if it were in worse condition ($400+) ?? How much time will you spend getting any rust off the bike (minutes or hours)?? How much is your time worth to you ??
A mid-level bike from the 1970's could be worth anywhere from $30 to $600, imho, depending on condition. Inflation is up 6x since the early 1970's a $600 bike would be that 1973 bike that was $150 new and was hardly ridden. a $60 bike has damage and needs many new parts. This bike sounds likie something in the $150 to $200 range in the early 1970's.
When i bought new bikes in the 1970's, i focused on bikes with balanced parts that i wouldn't have to upgrade. these are the cheapest bikes to own.
- Don Gillies
San Diego, CA