Re: extension kit for 58 evinrude lark 35
You should be able to find a 20" complete lower motor for a modest price on eBay. Alternately, it's the 'shorty' engines that are in demand, maybe sell yours complete & buy a complete 20". The OMC twins don't go for as much as the small Merc 4-cylinder shortys, which are more popular (great motors though).
