Well its worth a shot isn't it we never thought we was going to get sense 3 and I'm running 3.5
In fact my friend, we only have sense 3.5 because we were kind of lucky that HTC developped the HTC explorer.
Look, the first breaktrough with our hero was SalsaSense (Sense 2.2) from the htc salsa during summer 2011.
Then, we had the HTC explorer running sense 3.5.
Now, ask you the question : "Why is there no Sense 3.0 ROM?"
The answer is simple : there was no phone developped by HTC running sense 3.0 with the same arm architecture that our hero has!
Everytime we can port, it's because we have the same arm architecture. Just take a look at the ports, they are from : (htc armv6 devices)
HTC Aria
HTC ChaCha A810e
HTC Dream (T-Mobile G1, Android Dev Phone 1)
HTC Droid Eris
HTC Espresso (T-Mobile myTouch 3G Slide)
HTC Explorer (HTC Pico) (Armv6 and Armv7)
HTC Gratia (HTC Liberty)
HTC Hero (T-Mobile G2 Touch)
HTC Legend
HTC Magic (T-Mobile myTouch 3G, T-Mobile G1 Touch)
HTC Salsa
HTC Tattoo
HTC Wildfire A333
HTC Wildfire
HTC Wildfire S
Htc One series has different specs, really different specs. We had some hope because of Desire C because it had similar specs but at the beggining we did not know that it was another architecture.
In the end we had no boot, bootloops but it was impossible to get it boot correctly.
Just take a look at some threads on it :
Desire C port on WFS and Hero forums :
http://xdaforums.com/showthread.php?t=1655256 and
xdaforums.com/showthread.php?t=1658056 and
http://xdaforums.com/showthread.php?t=1660240
Different arm devices port :
http://xdaforums.com/showthread.php?t=1591878
So : yes it is possible, but no it hasn't been done yet because it's too complicated so far
well good luck if you want to do it
First thing you'll need to do is remove unnecessary apps(to make it fit to our amount of memory : maybe you'll want to take a look at amarullz ext system), then port the drivers to make it boot, and hopefully our hero would have enough ram to make it run correctly