it really depends what kind of lumpy cam it is doent really have any specs on the listing...
id say all off those mods you may be pulling the same as the 1600 or just slightly more to be honest.. the 1300 had around 60hp and the 1600 has about 80hp maybe cant quite remember off the top of my head. at the end off the day the horse power is going to come down to the cam and how big the jets and airflow is.
i think you would be better off just keeping the 1.6 in it or pulling it out and rebuilding it with sidedrafts, mild street cam and extractors, and a medium head port etc and youll be entering into the 100hp range if tuned out right.
hope that helps abit anyway