Bridgeport retrofit servo questions

OK guys...I've been reading posts on here for the past few days
regarding servo motors. After replacing a dead power transistor in my
BOSS 5 Bridgeport (just got it....Y axis DOA)...and spending way too
much time trying to interface to what appears to be a bad ERS board
(via serial)...I am now heading towards doing a complete retrofit of
the controls using Mach2.

I'm on the fence about whether to retain the working steppers and use
Larken stepper drives ($200 ea....up to 16A/ph) plus some type of
appropriate power supply, Campbells breakout and Mach2. The down side
of this may be that the machine doesn't move as fast as the BOSS
control can move it...but this is based on feedback from several
Gecko users on a BP. I am not looking to break any speed
barriers...but 50 IPM rapids aren't going to cut it. I need something
that can handle running several hours at a time. I saved for a while
to get the BOSS...now I have to scrape some $ together to do a
conversion...just so I can run the thing. I really don't want to do a
conversion twice (always time for that, right guys??!!)

The other choice that I have is to go with servos. The BP is
definately well into the servo side of the servo/stepper choice
threshold. Not partial to Gecko or Rutex as either will do (actually
I am because the Geckos are cheaper). I have read that several of you
suggest using some of the treadmill-type motors available from
surplus center. There are several DC dual shaft motors there with
pros and cons to each. I am curious as to what models would be best
for a BOSS machine. Here are a few that were mentioned...and a few
more that I picked out: (All listed can be found on this page:
http://www.surpluscenter.com/sort.asp?
UID=2005012813411678&catname=electric&keyword=MBDD )

1. $30. 10-1573 ~ 5100RPM rear shaft long enough for encoder off of
10-1834. Rated at 1.5 HP & 110v. Does this have enough juice for the
BP @ 75v? Current not advertised other than 1.4A no load.

2. $22. 10-1783/10-1783-A 2.5 HP rating 6750 RPM 18.5A 130v int duty,
95v continuous. Back shaft only .25" long. Will have to extend to use
any type of encoder. I am guessing that this would be a good motor if
run @ 75v/18.5A (within Gecko specs)...only thing I question is the
RPM/belt reduction. What ratio do you think is best on the BP with
this motor?

3. $80. 10-1906 2.0HP 130v/15A 3210RPM Continuous duty. Has good
shafts for driving and encoding. Shipping wt 24#s...starting to get
heavier. This seems like a good motor...the current rating tells me
that it has some cookies and the RPM is half of the previous
one...helping to curb insane reduction ratios.

4. $90. 10-1723 1.5HP 111v/7.6A 3100RPM 2-4hr rated continuous duty.
Looks like a good motor as well...but it is a pig. Ship wt @ 30# and
13" long...not liking that, but rotor inertia makes up for the length.

What do you think??? I think #3 so far might be a winner...yes it is
more $ than 1 & 2, but it has a beefy shaft on it, long enough in the
back for an encoder and the RPM isn't outlandish. I'd like 120 IPM
rapids and enough torque to mill at conservative speeds.

Sorry post is so long...I like to be as detailed as I can.

Thanks!!!
-Brady