Army;
Your sketch looks OK, and if you believe you understand the Alt (or Gen) based charging Sys, great! I agree a "Three-Wire Alt" should always be fitted to retain function of the AMP Indicator...anything less is just silly... See also:
http://www.sw-em.com/altkit_addition...ire_Alternator ...you may find other useful info on that page as it pertains to vintage Volvos, and Alt conversions thereof.
Your understanding of the differences in wiring between Gens (where ouput must be routed through VReg and its Cut-Out Contact, see:
http://www.sw-em.com/Bosch%20Generat...ut-out_contact ) and Alt, (where Output can be wired directly to into Elec Sys because uni-directional current carrying nature of rectifiers makes this unnecessary), is also correct.
On this page (
http://www.sw-em.com/elecramb.htm) which discusses the difference between Voltmeters and Ampmeters to monitor a vehicular elec sys, I have included the "H" diagram, which might help you further understand electrical generation, storage and usage, and current paths in a vehicle, and the way those play together.
Cheers