Both routes I'd be looking for a lender who has SBA PLP status and also has an appetite for hotel/special-use properties and construction of these properties.  

My appetite for REI is driven by the below mentioned traits that produce hefty rewards:LeverageCash flowAppreciation (forced, inflation and demand)Tax benefitsEquity building

I know as you mentioned classic cars are a big thing in our part of the country -- could  you start some sort of Guys/Car hangout - use the front office as a clubhouse - lots of old auto memorabilia there and in the warehouse (plus you'd have the fun of shopping for it), maybe install an automotive lift or two, great lighting - fire suppression system (would definitely make your insurance cheaper)? 

Let them know you are serious and that you have the means to close and I am sure you will find enough deals to satisfy your appetite. 

You would be amazed the appetite out there to find a reasonably safe investment with someone who they know, that pays them at least 8% (which is the usual preferred rate these days for investors to ask for).  

With potentially less marketability you may have to sell at a higher cap rate in order to unload the property in the future if that is a consideration.The other consideration pertaining to liquidity is the fact that some banks simply will not finance or offer much more restrictive programs for buildings with that type of unit mix so I would talk with local, regional, and national banks to see if they have an appetite for that type of collateral.

That being said, there are over 20 other municipalities in Pinellas County besides St Petersburg, and every city has it's own laws, rules, restrictions, and enforcement appetite/resources.Here is an interesting article that covers many of the issues:http://www.tampabay.com/news/localgovernment/pinel...

Start a discussion with the owner and gauge his appetite for wanting to sell and see if he has a price in mind.I am currently buying two properties from an owner referred to me through my property manager, at the moment we don't have a formal contract just a hand shake deal, since I told him I needed some time to wrap up a few other things first.  

I'd suggest driving around to get an appetite for the area: it's definitely a street-by-street sort of thing.As I've said elsewhere, I feel like the market here has heated up quite a bit in the last ~3 months, so it's been hard for us to find good deals, but maybe things will calm down in the winter.

@Dan Zhang  100 year old property will fall outside the appetite of most insurance carriers.