I think that the stock motor will handle a 150 shot if you do not use it frequently (daily). The cost for Nos kit is going to be in the $400 -$500 range. Then you will most likely want to get a remote bottle opener. Without the remote bottle opener you have manually open the bottle when you are planning on using it.
You should look into a supercharger. There are a bunch on ebay that you could get for a reduced price.