I just got back on here after a few weeks away, Really sorry to hear about your crank. Stock cranks will start breaking around 30-35hp, 30lb/ft torque. Quicker if there was a defect in the casting or previous stressing was too great. You are definately moving in the right direction with the Vogel forged crank for reliability and cost effectiveness. If you do weld up the block, here is what I have learned. 1:) hot tank the block first, then pre heat the entire block to 450 F. localized heating will/can cause stress after the welding process is over. For what you are wanting to do I would recomend brazing, you are after more of sealing up than taking stress in that area. DO NOT USE Nickel or stainless steel, it will fail and cause a weak zone all along the edge of the weld with this grade of cast iron, these are not high quality nodular iron blocks. If welding the ports for a massive build up I use cast iron, yes the old cast iron melting/welding process, any thing else I use brazing, do a good pre heat with the entire block, heat the area really strong and move out some just prior to brazing then use PLENTY of flux. The iron will accept the brass if properly done right more like capillary action. You can see the pores of the metal open up then thats the good time to start adding your brass.
Again, sorry about your mis-fortune with this, if there is anything I can do to help you just let me know or someone else know. This is a great site with a lot of good people willing to share and to help out!!
Good luck, Bruce