there's nothing wrong with modifying a carby engine. the americans are able to make 170whp with relatively light and cheap mods. you can buy engine kits at from the sponsors at
www.onecamonly.com for dirt cheap. the kits make it relatively easy to get the compression ratio in the 13s for less than a grand, as well as improving durability and the ability to cope with up to 10krpm. if you head down this path, you can match the power of a b16a, and it will cost less than doing a conversion to one. plus you get the better atomisation rate of a carby.