I would say no. More than an off-the-shelf converter? Yes. But we're not talking shortblock money (unless you goof the install and balloon the converter or take out your thrust bearing).
The short version is: any quality converter is going to be assembled or setup by the maker anyway and that's half the cost. So the tweaks necessary are really what you're paying for over the top of a shelf converter (which will take a million tries for a newbie to get right, and no one's going to take a used TC back). It's not like a 1/1 build, so rather than $3-400 you're probably in for $800+. If you're not looking to be competitive at the local purse events, then you're probably going to stay pretty close to that $800 range from what I gather. Competitive setups can run a helluva lot more.
The big take-away is: don't pick one yourself from a catalog. Call up the experts and let them help, but help them by being very honest and give plenty of detail and all the data you can. If you don't have the info (like peak torque RPM), ask them 'what can I do to help fill in the blanks?' and let them give you some direction.
Even if the first try isn't perfect, it's usually not *too* expensive to rework a converter to get it 'right'. This also applies for down the road when you put together an 11:1 shortblock with some free flowing heads - just send the TC back for an update.
