Have a look on Guy Crofts website.....its not good news! They are a poor flowing heads and definately require a flow bench to get improvements.
Every head I've seen for sale that has been 'gas flowed' does not have any flow bench data to back it up, so any porting may have done more damage than good!
To get 120/130 out of an 8v will take considerable time and money. If you can start with a 1242 block then you'll have a better chance.
BigElmo and another built some high power N/A motors. Your talking bigger valves, smaller stems, 300+degree cam, top hat shims and followers to suit and carbs or ITBs.
I've got a 1242 16v block bored out to 1299cc with an 8v head on it and ITBs with 8 injectors. Should make some decent power if it ever makes it into a shell.