Homemade HV transformer

["Garth van Sittert" <garth-at-mediasupplies.co.za> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

I have a large laminated core and bobbins only with no primary or secondary
(ie: no copper at all) that I am hoping to wind for coil use.  The core is 2" x
2".  Bobbins are 6" high.  What sort of VA ratings could I get out of this,
3600VA.  
 
So far I have calculated -at- 50 Hz 220V 
    primary:    275 turns   (This gives me an excitation current of 10% of the
propposed max. primary current).
    secondary: 15000 turns (12kV -at- 300mA)
 
Is this correct.  
 
Firstly, I wound the primary bobbin with #22 wire for test purposes about 400
turns, and then reduced the turns until I had a no load current of 1.5A (10% of
max.)  This gave me the required turns per volt.  Now I intend to wind the
primary with 275 turns of max guage wire I can fit onto the bobbin.
 
I saw some general rule somewhere that turns per volt = 5/A where A is the core
area in sq. inches.
 
Will this blow up or have I gone about this correctly.
 
Thanks
Garth.