haha mmm the crossroads.... Keep spending money on your v6 and making it look the goods but worry you may have to start again as it will just never satisfy compared to a v8. If it were upto me I'd stick with the car you have and do the conversion piece by piece. The cost may be more in the end but it will happen in increments and you won't lose out on your current mods (you're not going to get what you paid for with regards to the physical mods back if you sell it). Things i'm pretty sure that will need to be done which would probably make your car better anyways
Brakes
Suspension (in the front I think is slightly different on the SS to cover the extra weight)
Transmission, cost like 2k brand new out of Street Machines mag, thats the T56 i think.
I think the SS radiator is slightly different? Takes oil or something? not sure
Majority of the wiring engine wise
I'd say the best bet would be to accumulate bits in pieces as you go, finding 1 getting wrecked would be the best bet, always pop up on ebay selling items cheap as chips. LS3 or LS7 would be the way to go I reckon just to keep it different from the majority of SS's.
Scores of people do engine conversions all the time, get some professional advice and see where you end up.
You could alternatively wait and see how technology comes along with the sidi engines, cams look promising; wack a supercharger on there down the track and it should go harder than a stock SS, maybe even the majority that get the otr/catback/tune combo but thats uncertain. Of course you will be lacking the sound and the overall possibilities of the v8 engine, but if you want to keep it streetable you can't really go over the top.
I think its totally upto you mate, if you don't want the hassle then trade-up. But you will have to start at square 1 again and you've already made a fair bit of effort. Betting if you got the conversion done successfully aswell you'd be on the cards for a feature in a magazine, seen cars get in for MUCH less.
Slightly off topic, a guy on ProUtes got his ve alloytec cammed recently and it sounds pretty damn nice, really lumpy idle. Still waiting on the tune though so might be a decent indicator how much steve can get out of the sidi and i'll keep you posted on that if you're interested.