Rocky Roads

I have a 1985 Chevy Van with a carburated 305. It takes three 5 second cranks to get started when it has set for more than 2 days. The next day after running it starts right up. I have removed the carb and sealed the ports on the bottom. After that didn't solve the starting problems I removed the carb again to see if I did a bad job on the plugs. Everything was dry and looked good. I don't know what else to try other than install an electric fuel pump to charge the carb before an extended start. I'm open to any suggestions. But if I continue with my plan, I have a couple of questions. Should I install the electric pump in parallel or series with the mechanical pump? If I put it in parallel the line from the stock pump to the carb is solid. Can this be replaced with rubber? Why did they make it solid? If I put the electric pump in series it would be easier before the mechanical. Is this ok? Thanks for any assistance.