Aren't the upper bushes the same as a 140?
No, they are not the same.
The 140 upper wishbone and shaft are different - the 140 upper wishbone shaft is male threaded, and the bushes are held on by nuts; with the 164, the wishbone shaft is female threaded, and the bushes are held in place to the shaft by bolts.
164 part numbers for upper wishbone, etc
688022 - wishbone (L) 688023 = wishbone (R)
679246 = shaft
679247 = forward bush
679248 = rearward bush
See 164 parts manual, Grupp 6, Sida 30.
VP Autoparts have both as a special order item.
http://www.vp-autoparts.com/eu/main.aspx?page=article&artno=1404080104&startoffset=0
Pelican Parts say they have the 679247 and 679248 in stock.
http://www.pelicanparts.com/More_Info2/679247.htm?pn=679247
http://www.pelicanparts.com/More_Info2/679248.htm?pn=679248
This is an alternative for the 679247:
http://www.skandix.de/en/spare-parts/suspension-steering/axle-mounting/bushing/bushing-suspension-front-axle-control-arm-upper-front/1054287/?bi=ceb084deb3a7a442b9e5ed77aa3fb30c
This is an alternative for the 679248:
http://www.skandix.de/en/spare-parts/suspension-steering/axle-mounting/bushing/bushing-suspension-front-axle-control-arm-upper-rear/1010940/
Swedish Auto has them on backorder at present.
http://www.swedishautoparts.com/160/Volvo-160-suspension-front.html