would have been worth more without that FSU sticker...
Great looking rig. Can't blame you for wanting to change the engine, just know that there are very few of these left as (seemingly) stock as what you have there, and if your appraiser actually knew what he was doing, that would be a big part of that 15 - 17k number. In other words, changing that engine will probably drive the real value down.
That said, it's your horse and you have to ride it: if you want a V8, get a V8. 40's are a lot of fun, but mostly when you drive them.