You can use any lens with this enlarger, although I sometimes had a
hard time insetering a Nikkor 210mm because of the lens board stage on
my 45 MXT (and even on the VXL series...I have both).  For some
reason, Beseler decided not to cut the lens board stage all the way
(there's this arc shaped amount of steel that there is no reason why
it should be there...except to make inserting some lenses difficult,
thus making you buy the Beseler HD series of lenses!) and the back
barrel of the Nikkor 210 is rather large.  Other than that, any lens
will work.  but when using this head with smaller formats, where you
put the negative depends on which lens you can use.  More on that
below.

I did this same thing, for a variety of reasons.  First, I like to use
my Zone VI compensating timer and its feature of being able to adjust
the light output for meticulous dodges.  THIS FEATURE WILL NOT WORK
WITH 8X10 HEADS UNLESS THEY ARE MODIFIED AND YOU CAN RUIN YOUR TIMER
AND HEAD BY TRYING TO USE IT!  Sorry to yell, but this is very
important.  So, when I was doing 4x5 format and smaller, I'd simply
lift out the 4x5 Zone VI head (a "coller" comes with, or should, the
8x10 conversion kit that "holds" 4x5 heads (cold light, condenser
types) in place, since the "hole" of the conversion kit is slightly
larger than the standard hole for heads on the 45 series.), put on a
little shelf I'd built next to the chassis, put the 810 negative stage
on and lift on the 810 head.  Takes all of 3 minutes.  You CAN use any
compensating timer with the head, provided the head has, or you insert
one yourself, a photo cell probe, BUT unless you modify the
transistor, or whatever the power supply thing for the head is called
(beselers is internal these days, where as the original by Aristo had
an external one) you'll damage either, or possibly both, the head and
timer if you try and use the light output feature on the Zone VI
timer.

The 810 head will provide plenty, if not more, output than the 4x5
head.  The original neg stage, where you currently put your negs,
remains and can be used after the kit is installed.  There are times,
like when I wanted to print a 4x5 negs with the rebate edge or a whole
poloroid 4x5 neg, that I had to use the 810 head and a 150 lens,
because of the print size.  To do this, you will need to take out the
glass 810 neg/diffuser thing from the 810 neg housing, flip the neg
housing upside down, reinsert the neg/diffuser thing (diffuser side
up, glass down) and slide the head "INTO" what is normally the bottom
of the 810 neg housing.  IT took me half a day to figure that one out,
Beseler doesn't inform you of such things, but it works like a charm

No problem.  If you need further help, just email me.

Good luck

Alexis

www.alexisneel.com