And could you give me a brief summary as to why if I am using a 220 volt line for the HV transformer that it makes a difference if the 115 voltage is taken all off one side or if it is balanced between the two legs.
That's easy.... The advertised current rating of the transformer assumes proper inductive coupling between the primary and secondary. If you use only half the primary winding you can't expect a full strength field (and rated current) in either the core laminations or any secondary winding. Worse yet, remember the windings are stacked in layers. For the sake of a mental image, let's assume the primary is nearest the core (and they almost always are). Visualize two layers of winding, center tap, then another two layers on top of that. If you energize the first half you have two layers of 'dead' copper between the primary and secondary windings. Energize only the second half and the primary winding is now two layers distant from the core and the resultant flux strength will be less than optimum.
If the primary is split into two 120 VAC windings you can parallel them for 120 or series connect them for 240 AS LONG AS THEY'RE IN PHASE!
Get the phasing wrong and the windings will get real hot real fast and there's a chance you won't pull the plug fast enough to avert transformer death by induction. Been there, done that, best advice is to pre-connect a voltmeter or install a lightweight fuse prior to the first attempt at fire in the hole. Hit the switch and any twitch of the meter below what's expected prompts you to shut it off instantly.
BTW: Been my experience that tapped primaries are rare. I've seen it in Japanese equipment with a 120 volt primary tapped at 100 volts for domestic use, but aside from that a split primary is usually on lugs 1 & 2 / 3 & 4 and measure near-identical resistance with an Ohmmeter. Parallel connection is odd to odd (1 to 3) and even to even (2 to 4). Series would be 2 to 3 with AC on 1 and 4. Your transformer could be completely different and what you think is the primary may well be a secondary...... If you have pigtail leads look for black and black with colored stripe. Green is 5 VAC rectifier filament, Yellow is 6.3 VAC filament, Red is HV.
Your Mileage May Vary. Research and test as best you can before applying power.