reviving old seacraft (propeller question)

[bitsamonkey]

Hi, and thanks for this cool website!
I recently got a '69 seacraft center console with an 80's carbed Merc 200 V6. I know it's way too much engine for this boat, but it's what I got.
It gets this little boat going in a hurry, but seems under propped at wot. So I was wondering what size prop you guys that have similar rigs use. The boat is super light with no top, no livewell, no extra nothing and will stay this way.