56.5" X 11.125" chord X 15.5%airfoil, 49" nose totail, 18-20 oz. wing load..... given those parameters, would a .46 be enough for enjoyable, "easy-does-it" flying?

Yes

Copied from

http://adamone.rchomepage.com/design.htm

Recommended Engine Size vs
Wing Area
c. in. area sq. in.
.049 200 - 250
.10 250 - 350
.15 300 - 450
.25 400 - 500
.40 500 - 700
.60 600 - 850

"Powered model aircraft performance may also be estimated by calculating the
weight / power ratio, also known as power loading.
A slow and low wing loading (for a beginner), with a weight / power ratio of 440
to 500g/c.c. (270 to 300oz/c.in.) might be good enough, whereas an aerobatics
would need about 340g/c.c. (200oz/c.in.) to achieve good performance.
This is assuming 2-stroke engines and that the power of different types is pro-
portional to their displacements, (which isn't too far off)."

  thanks again, Lnewqban....
       this is for that same plane. when i blew the prints up, i studied as many specs as as could find to come up with a suitable expansion number. as it is getting nearer the covering stage, i find myself questioning it's weight because it's it seems to me that it's got a good bit of wood in it.  i've seen most of the spread sheets dealing with weight, size, volume, etc and engine size, i just wanted to run by you guys with more building experience.
      funny thing happens as you get older..... you realize you don't know everything and discover it's not a bad thing to refer to experienced knowledge!!.
                         you've been helpful,
                                          ron.