I have had a pair of 1984 LaScalas since new. Earlier this year replaced th tweeters with the Crites CT125 and the crossover with the Crites Type A/4500 crossover. I just recently added a JL Audio F113. Tons of nice tight bass down below 20Hz at full volume ( my room correction is turning down the bass below 20 Hz to make it blend right), mate up to the LaScala's like they were made for each other ). Still considering replacing the woofers in the LaScalas as they have been in service since 1987 ( blew one in 1987 ).
If I had it to do over again, I wouldn't deviate. You can't get deep bass out of the LaScala, it just isn't made for it. As for the porting option, you will lose the nice tight bass you have to get a sloppy lower octave ( this is just my opinion here ). Also, from what I've been reading, the cast-basket Crites woofers may get you a little better bass, but some people are having to gouge out wood to make room for them in their LaScala's. I may also replace my mids sooner or later ( seems to me that 25 years is a lot to ask, but I'm not sure how long they should really last).