Help Speaker replacement advice needed

Hi,
I found some old Marantz boxes in the attic. LD20 if that means
anything to anybody anymore, probably not. 14" by 9" by 10"
outside, 2 way, vented. Foam turned to dust on bass units.

Since all I have is two probably usefull ready-made enclosures
my question is what speakers should I get to use there. Not
expensive and available in UK. I would appreciate your
recomendations.

The original tweeters might work but the quality? The mid/bass
opening is 168mm, centre to centre is 143mm. All openings can
be cut bigger, vent can be closed, etc.

Is there any info site where I can compare dimensions or find
calculations to arrive at proper crossover frequencies. Maybe
manufactors datasheet sites? My old ref books are gone and any
math background I had went with them.

It was long ago since I DIY-ed speakers and the old favorites
are irelevant today probably.

Thanks
ayosha