Carb wise you have 3 options… OEM  from a dealer     Chineese on AMAZON ( some gaskets have been reported melting like goo…and  needle seats   with bad threads

OEM whith stuff possible made  in China these days .

in general Sierra stuff seems fairly good (opinions differ)

Magneto wise    OEM stuff  as always $$$   or  coils from AMAZON at 20$ each    some points  sets  are increasingly  reported  ” not no good anymore better to  clean up the old ones if still good  ”      and some   simply  mechanically unfit

Condensers  available from dealers  or Amazon ..

do not use carbon based wires.

solid  strand copper  wires are best  from a local  bike/mower shop   or Amazon .   I install  solid  strand wire  kits  (Belden) for cars  with end plugs installed.

http://www.youtube.com/watch?v=ga1Cjymj6ms&feature=youtu.be

Did you check/change the gear lube?  Is the compression OK?

OEM carb kits are still available for that engine.  OEM “tune up kits” are available as well, but you will need a decent flywheel puller in order to get at the ignition components.